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Best Selling Genuine Geo O2 Sensors

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We stock O2 Sensor parts for most Geo models, including Metro, Prizm, Storm, Tracker.

Bosch
Qty:
$24.57
Bosch Oxygen Sensor  Upstream
  • Bosch Oxygen Sensor
  • Universal Oxygen Sensor
  • Product Attributes:
    • Automotive Item Weight (lbs): 0.182984 Lb
    • Connector Shape: None
    • Hex Size (Oxygen Sensor): 22 Mm
    • Length (Sealing Surface To End Of Connector): 5.314964 In
    • Mounting Type: Threaded
    • Oxygen Sensor Type: Narrow-band Non-heated
    • Sensor Type: Non Heated
    • Wiring Harness Length: 6.5
  • Bosch leads the way in oxygen sensor technology and innovation. From overall sensor design to the critical ceramic element, Bosch is known worldwide for quality and performance.
  • Suggested Purchase Quantity: 2
    • Most jobs typically require 2 of this item.
Brand: Bosch
Position: Upstream
Additional Fitment Information:
Vehicle Position Block Engine CID CC
1990 - Geo Tracker Upstream L 4 Cyl 1.6L 98 1588
Bosch
Qty:
$23.76
Bosch Oxygen Sensor  Upstream
  • Bosch Oxygen Sensor
  • Actual OE Oxygen Sensor
  • Product Attributes:
    • Automotive Item Weight (lbs): 0.17637 Lb
    • Connector Shape: Male Pin
    • Hex Size (Oxygen Sensor): 22 Mm
    • Length (Sealing Surface To End Of Connector): 14.566937 In
    • Mounting Type: Threaded
    • Oxygen Sensor Type: Narrow-band Non-heated
    • Sensor Type: Non Heated
  • Bosch leads the way in oxygen sensor technology and innovation. From overall sensor design to the critical ceramic element, Bosch is known worldwide for quality and performance.
  • Suggested Purchase Quantity: 2
    • Most jobs typically require 2 of this item.
Brand: Bosch
Position: Upstream
Additional Fitment Information:
Vehicle Position Block Engine CID CC
1989 - Geo Spectrum Upstream L 4 Cyl 1.5L 92 1471
Bosch
Qty:
$24.57
Bosch Oxygen Sensor  Upstream
  • Bosch Oxygen Sensor
  • without California Emissions
  • Universal Oxygen Sensor
  • Product Attributes:
    • Automotive Item Weight (lbs): 0.182984 Lb
    • Connector Shape: None
    • Hex Size (Oxygen Sensor): 22 Mm
    • Length (Sealing Surface To End Of Connector): 5.314964 In
    • Mounting Type: Threaded
    • Oxygen Sensor Type: Narrow-band Non-heated
    • Sensor Type: Non Heated
    • Wiring Harness Length: 6.5
  • Bosch leads the way in oxygen sensor technology and innovation. From overall sensor design to the critical ceramic element, Bosch is known worldwide for quality and performance.
  • Suggested Purchase Quantity: 2
    • Most jobs typically require 2 of this item.
Brand: Bosch
Position: Upstream
Additional Fitment Information:
Vehicle Position Block Engine CID CC
1994 - Geo Metro Upstream L 3 Cyl 1.0L 61 993
Bosch
Qty:
$23.76
Bosch Oxygen Sensor  Upstream
  • Bosch Oxygen Sensor
  • without California Emissions
  • Actual OE Oxygen Sensor
  • Product Attributes:
    • Automotive Item Weight (lbs): 0.17637 Lb
    • Connector Shape: Male Pin
    • Hex Size (Oxygen Sensor): 22 Mm
    • Length (Sealing Surface To End Of Connector): 14.566937 In
    • Mounting Type: Threaded
    • Oxygen Sensor Type: Narrow-band Non-heated
    • Sensor Type: Non Heated
  • Bosch leads the way in oxygen sensor technology and innovation. From overall sensor design to the critical ceramic element, Bosch is known worldwide for quality and performance.
  • Suggested Purchase Quantity: 2
    • Most jobs typically require 2 of this item.
Brand: Bosch
Position: Upstream
Additional Fitment Information:
Vehicle Position Block Engine CID CC
1994 - Geo Metro Upstream L 3 Cyl 1.0L 61 993
Bosch
Qty:
$23.76
Bosch Oxygen Sensor  Upstream
  • Bosch Oxygen Sensor
  • Bosch Engineered Oxygen Sensor
  • Product Attributes:
    • Automotive Item Weight (lbs): 0.17637 Lb
    • Connector Shape: Male Pin
    • Hex Size (Oxygen Sensor): 22 Mm
    • Length (Sealing Surface To End Of Connector): 14.566937 In
    • Mounting Type: Threaded
    • Oxygen Sensor Type: Narrow-band Non-heated
    • Sensor Type: Non Heated
  • Bosch leads the way in oxygen sensor technology and innovation. From overall sensor design to the critical ceramic element, Bosch is known worldwide for quality and performance.
  • Suggested Purchase Quantity: 2
    • Most jobs typically require 2 of this item.
Brand: Bosch
Position: Upstream
Additional Fitment Information:
Vehicle Position Block Engine CID CC
1993 - Geo Storm Upstream L 4 Cyl 1.6L 98 1588
Denso
1997 Geo Tracker Oxygen Sensor - Upstream 4 Cyl 1.6L Denso - OE Style

P311-08CF2E4    234-4060  New

ES20191 , 91177408 , 13073 , 24617 , 75-1825 , OS616 , 1821358B11 , 213-3131 , 1821358B00 , 1821358B21 , SG411 , ES10963 , 213-1362 , 21508 , 213-404 , 213-2940

Qty:
$62.90
Denso Oxygen Sensor  Upstream
  • Oxygen Sensor 4 Wire, Direct Fit, Heated, Wire Length: 21.26
  • OE Style
  • Product Attributes:
    • Mounting Type: Threaded
    • Sensor Type: Heated
    • Thread Diameter: 0.708
    • Wiring Harness Length: 21.26
  • DENSO Oxygen Sensors are manufactured and tested to the strictest OE standards for unparalleled peformance; Each component is precision built for exact replacement, and a first time fit; This innovative line features DENSO's exclusive aluminum oxide trap layer, designed to protect the ceramic element from silicone and lead posining for improved engine performance, greater fuel efficiency, and unparalleled longevity; DENSO gives you the right part and the right fit, the first time.
Brand: Denso
Position: Upstream
Additional Fitment Information:
Vehicle Position Block Engine CID CC
1997 - Geo Tracker Upstream L 4 Cyl 1.6L 98 1588
Denso
1990 Geo Tracker Oxygen Sensor - Upstream 4 Cyl 1.6L Denso - OE Style

P311-2A017A6    234-1009  New

1821361A10 , 96058082 , SG13 , 36531PD2305 , 17217250019 , 15396 , ES10964 , 75-2889 , OS510 , 213-1172 , 213-1191 , 24033 , 17217250031 , 17217250035 , 36531PH7305 , 1821383000 , 19219220053 , 36531PR4L02 , 36531PP0N02 , 36531PM8305 , 36531PH2024 , 36531PL2023 , 17217250020 , 17217250032 , 36531PM5L02 , ES10672 , 36531PN4N02 , 96051853 , 36531PJ0L02 , 213-403 , 12050

Qty:
$23.11
Denso Oxygen Sensor  Upstream
  • Oxygen Sensor 1 Wire, Direct Fit, Unheated, Wire Length: 18.82
  • OE Style
  • Product Attributes:
    • Connector Gender: Female
    • Mounting Type: Threaded
    • Sensor Type: Non Heated
    • Thread Diameter: 0.708
    • Wiring Harness Length: 18.82
  • DENSO Oxygen Sensors are manufactured and tested to the strictest OE standards for unparalleled peformance; Each component is precision built for exact replacement, and a first time fit; This innovative line features DENSO's exclusive aluminum oxide trap layer, designed to protect the ceramic element from silicone and lead posining for improved engine performance, greater fuel efficiency, and unparalleled longevity; DENSO gives you the right part and the right fit, the first time.
Brand: Denso
Position: Upstream
Additional Fitment Information:
Vehicle Position Block Engine CID CC
1990 - Geo Tracker Upstream L 4 Cyl 1.6L 98 1588
Denso
1992 Geo Tracker Oxygen Sensor - Upstream 4 Cyl 1.6L Denso - Universal

P311-403154B    234-3000  New

75-1545 , 25507 , 13003 , 25506 , 213-1242 , ES10229 , SG79 , 75-1560 , 92860612400 , 92860612800 , OS521 , 13918 , OS516 , 94460613500 , 15735 , SG62 , 213-1241 , ES10241 , SG63

Qty:
$41.10
Denso Oxygen Sensor  Upstream
  • Oxygen Sensor 3 Wire, Universal, Heated, Wire Length: 11.77
  • Universal
  • Product Attributes:
    • Mounting Type: Threaded
    • Sensor Type: Heated
    • Thread Diameter: 0.708
    • Wiring Harness Length: 11.77
  • DENSO Oxygen Sensors are manufactured and tested to the strictest OE standards for unparalleled peformance; Each component is precision built for exact replacement, and a first time fit; This innovative line features DENSO's exclusive aluminum oxide trap layer, designed to protect the ceramic element from silicone and lead posining for improved engine performance, greater fuel efficiency, and unparalleled longevity; DENSO gives you the right part and the right fit, the first time.
Brand: Denso
Position: Upstream
Additional Fitment Information:
Vehicle Position Block Engine CID CC
1992 - Geo Tracker Upstream L 4 Cyl 1.6L 98 1588
Denso
1995 Geo Prizm Oxygen Sensor - Upstream 4 Cyl 1.6L Denso - OE Style

P311-1577023    234-2052  New

ES10318 , 75-1561 , 213-1521 , SG361 , 24511 , OS595 , 12201 , OS620 , OS593 , 8946519405 , 8946529415 , SG355 , 8946519535 , 94854938 , SG81 , 213-1213 , 8946529745

Qty:
$38.20
Denso Oxygen Sensor  Upstream
  • Oxygen Sensor 2 Wire, Direct Fit, Unheated, Wire Length: 35.2
  • Excludes Calif.
  • OE Style
  • Product Attributes:
    • Sensor Type: Non Heated
    • Wiring Harness Length: 17.80
  • DENSO Oxygen Sensors are manufactured and tested to the strictest OE standards for unparalleled peformance; Each component is precision built for exact replacement, and a first time fit; This innovative line features DENSO's exclusive aluminum oxide trap layer, designed to protect the ceramic element from silicone and lead posining for improved engine performance, greater fuel efficiency, and unparalleled longevity; DENSO gives you the right part and the right fit, the first time.
Brand: Denso
Position: Upstream
Additional Fitment Information:
Vehicle Position Block Engine CID CC
1995 - Geo Prizm Upstream L 4 Cyl 1.6L 98 1588
Denso
1991 Geo Storm Oxygen Sensor - Upstream 4 Cyl 1.6L Denso - Universal

P311-0CD2B4E    234-1000  New

SG8 , 75-1562 , 11051 , SG88 , OS2043 , 23044 , 213-1182 , 025906265 , 0060733358 , 75-1558 , 11964 , SG600 , OS569 , ES10587 , 75-1506 , 11032 , ES10277 , 25139 , 0025421218 , 25031 , 11027 , SG58 , 25503 , 051906265E , SG83 , 200906265A , SG1241 , 12040 , 25088 , 25500 , No Coverage , 25501 , 75-3341 , 94460613300 , 039906265 , 213-2863 , 91160612300

Qty:
$14.03
Denso Oxygen Sensor  Upstream
  • Oxygen Sensor 1 Wire, Universal, Unheated, Wire Length: 11.77
  • VIN 6
  • Universal
  • Product Attributes:
    • Mounting Type: Threaded
    • Sensor Type: Non Heated
    • Thread Diameter: 0.708
    • Wiring Harness Length: 11.77
  • DENSO Oxygen Sensors are manufactured and tested to the strictest OE standards for unparalleled peformance; Each component is precision built for exact replacement, and a first time fit; This innovative line features DENSO's exclusive aluminum oxide trap layer, designed to protect the ceramic element from silicone and lead posining for improved engine performance, greater fuel efficiency, and unparalleled longevity; DENSO gives you the right part and the right fit, the first time.
Brand: Denso
Position: Upstream
Additional Fitment Information:
Vehicle Engine VIN Position Block Engine CID CC
1991 - Geo Storm 6 Upstream L 4 Cyl 1.6L 98 1588

Latest Geo Repair and O2 Sensor Installation Advice

CarJunky AutoAdvice

geo tracker running rough no power

Showing 2 out of 2 Posts
Question From jk4fish on geo tracker running rough no power

I have an 1997 geo tracker 4 cylinder manuel tran.morning after first freeze started running really rough with no power. auto zone code thingy said " multiple cylinder missfire and o2 sensor system failure or something close.When i unplug the lead to the o2 sensor upstream of the converter it runs the same. I,m relatively poor and can't afford to chase this around at christmas. 3 kids. $70 sensor. safe bet or not? can I check it without being out $70? thank you James Knies

Response From steve01832 Top Rated Answer

The odds of an O2 sensor causing a multiple misfire are slim to none, and slim just left. You would more or less be looking at ignition system components. I would start with testing spark at all cylinders with a spark tester. Check the plugs also. You could have a cracked distributor cap or a bad coil pack depending on the system your vehicle has. Sorry, I don't have a shop manual in front of me right now to check.

Steve

os sensors

Showing 7 out of 8 Posts | Show 1 Hidden Posts
Question From jnlcars on os sensors

on a 1997 geo prizm with a 1.6 motor with 174863 miles/3 sp A/T a transmission the check engine light came on with codes po130 witch is pre-converter o2sensor an a po133 witch is a pre-converter o2 sensor circuit slow response fault an a po135 pre-converter o2 sensor heater fault i have replaced both o2sensors as well as as throttle position switch egr valve along with a tune up plugs cap rotor wires timein belt car starts but uses way to much gas an takes forever to get to speed. like said i have relaced both o2 sensors an started testing wires an right now at a dead end please help wife car

Response From Discretesignals

Welp, as you know now just because there is an O2 code doesn't necessary mean the O2 is the culprit. That is a trap that most people fall in.


You need to do some prelim checks. Your not going to be able to do much without a scan tool and some engine data information.

You can start by checking fuel pressure with a gauge while the problem is occurring. Fuel pressure should be around 38-44 psi and shouldn't drop out under acceleration. You mentioned you believe it was running rich. Check the fuel pressure regulator and make sure it isn't leaking on the vacuum side. You could have injector flow problems, but you need special tools to be able to diagnose that properly. Also check for vacuum leaks.

Response From jnlcars Top Rated Answer

you are right about that with the o2 sensors throwing a code a ghost code. i have checked all the following and everything checked out fine. but there was one problem that was unseen!!! apparently somebody else has had a similar problem an and had it fixed before the wiring was all cut up and bare wires were exposed after the electric tape had came apart under the plastic sleeve there was no shielding in place as it was shorting out several other components but ty

Response From Hammer Time

you are right about that with the o2 sensors throwing a code a ghost code.

Ghost code?......... No such thing, only problems that techs can't figure out

Response From Tom Greenleaf

Miles and now poor acceleration/power AND using too much fuel I'd be check for exhaust restriction(s) as too unburned much fuel can overload a converter in fairly short order from the initial problem,

T

Response From jnlcars

for everyone my problem was the engine wiring harness that falls though the fire wall and connects to the ecm an its fixed ty

Response From Sidom

Yea...no kidding on finding it..............good job..............I hate tracing shorts..........

Response From Hammer Time

See, someone else would have given up and just called it a "ghost code".

Congrats on finding it.

o2 sensor replacement downstream

Showing 2 out of 7 Posts | Show 5 Hidden Posts
Question From rosekurcik on o2 sensor replacement downstream

Hey! I have a 1998 toyota corolla le 1.8L. I'm trying to replace the downstream 02 sensor (after the cat). I located the sensor but don't know how to get to the connector. All the videos I watched had the connector just running along the exhaust frame. My car has it up under a metal plate that I guess I have to remove(pain in the ass). Is this how I get to it?? I wanna be sure before I jack the car up. Thanks for the help!

Response From Discretesignals

You have to remove the passenger side seat. The connector is under the carpet.

Response From flidgeman Top Rated Answer

hi i was wondering if you could help me with my 97geo
prizm?

Response From Hammer Time

Please read the FORUM RULES

Response From rosekurcik

Thanks for the response. This sounds like alot more work than I expected. I can take the seat out easy enough, but is there alot more steps after that or is it a pretty easy installation? I'm trying to save money by doing it myself. I'm a poor college student!!

Response From Discretesignals

Once you get the seat out and the carpet up, you understand what you have to do to remove the O2 sensor.

I can't remember if you have to unbolt the heat shield on that one and drop it down. I work on so many cars everyday, I can't remember my first name..

Response From nickwarner

I think being you live in a state that salts their roads you may want to take this one in. If you are broke you likely do not have the proper tools to get a frozen sensor out. A lot of times with a salted car I end up having to weld in a new threaded bung because the threads pull out when trying to remove the O2. I'm guessing you don't have a welder.

Wanted to warn you ahead of time what you might be up against. I live in WI so I get to see the evils of salt.

Help my MPG

Showing 2 out of 2 Posts
Question From cabuys on Help my MPG

I have a 1997 GEO tracker, and got water in the gas tank, since got that cleared up but my gas milage went from 30-33 mpg down to 20 mpg, I changed the plug, rotor cap and distr cap, fuel filter and the catylitic converter although it runs better the gas milage is still only 20 mpg, any other suggestions of things that need to be checked?

Response From DanD Top Rated Answer

O2 sensor?

p0125 (Insufficient Coolant Temperature For Closed Loop Fuel Control)

Showing 2 out of 16 Posts | Show 14 Hidden Posts
Question From completelyhis on p0125 (Insufficient Coolant Temperature For Closed Loop Fuel Control)

1997 Geo Prism, 1.6 liter, 175k miles.

I get a P0125 (Insufficient Coolant Temperature For Closed Loop Fuel Control). I have changed the temperature sensor, thermostat, checked coolant level, repaired the exhaust lead that was @ the doughnut flange, and then replaced the front o2 sensor.

The engine gets to "normal" operating temperature w/in a normal time (a few minutes). It runs great. When I clear the code, it comes back within 10 miles or less after clearing it.

I read this here
link deleted............. not allowed

I know that the drive train for the prism is a toyota drive train, so that conversation is relavent, but I don't see a solution I haven't tried.

Any suggestions?

Thanks,

Ian

Response From DRND

I have good experience with this code with toyota 1nz-fe engine i reset code but it take after 15km - 35km
So.....
You should check your system clearly by using car scanner and look at ECT,O2 B1 S1,O2 B2 S2 sensor's values.some time u will feel O2 B1 S1 value is less than other O2 sensor value.but it's OK because O2 sensor locate at after cat(per-cat).but clearly monitor your O2 B1 sensor's value is less than 0.1mv. the ECM monitor this value in time period and set this code
So i swap O2 B1 and O2 B2 sensor then O2 B1 reading was ok.after i drive 100km but not it take this code

Response From Tom Greenleaf

Sport - this is about THREE years old! Please stick to current threads. Locked for archives and keep spammers out now,

T

Response From Hammer Time

I've never heard such an idiotic response either.

Response From Hammer Time

You really need a scan tool so you can monitor what temp the computer is seeing and you can then determine if and where the problem is.

Response From completelyhis

i assume that's different than my "auto xray" code reader? Can you recommend a good scan tool?

Response From Sidom

I think HT is right and it's going to be a temp sensor problem...... Most of the time with this code you have a stuck open T stat. If this code is setting within 10 minutes during this time of the year, it would have to be a electrical problem.

How's it run? Any black smoke out the back or hard starting????

Response From completelyhis

no smoke, starts great runs solid and strong. replaced Tstat and temp sensor. I replaced the one that's on the thermostat housing, with a two-wire harness connected to it...is that the right one?

electrical problem...could you elaborate?

Ian

Response From Tom Greenleaf

You can OHM test CTS and should show that it changes as engine warms up. I don't have the range but most are fine or do nothing. The plug can be the problem,

T

Response From Hammer Time

I think your wasting your time with those types of tests. The code here is indicating that there is insufficient temp for closed loop. I have had to deal with this code before. This can come down to a matter of just a couple degrees so unless you see the exact digital temp that the computer is seeing, your not going to solve this problem. I had one that continuously failed emission but never set any codes and it turned out to be the calibration of the thermostat. It was only about 5 degrees low but that was enough to prevent it from going into closed loop and in turn made it fail emissions.

Response From completelyhis Top Rated Answer

I took the car to a guy who has the ability to read the ECM data and it ends up that the computer is reading zero's from the o2 sensor.

i did some research and found these suggestions:

Verify continuity between the ECM and O2 Sensor
Make sure that there is 12 V making it to the O2 sensor
Check the resistance of the sensor (should be between 11 and 17 Ohms).
Are those good things to check? Any other testing I could/should do? I assume it's either bad wiring or a bad ECM. Is that a safe assumption? Where is the ECM on the 97 prism, so I can check continuity between it and the o2 sensor? Is there any reason to check the resistance of the sensor other than confirming if the sensor is good or not?

Thanks,

Ian

Response From Hammer Time

That has nothing to do with the code you are getting. I actually find that hard to believe since you don't have any lean codes.

Response From completelyhis

I looked at the device he had hooked up to it while it was hooked up, i saw the MAF readings and all the other ones updating in real time. the o2 was zero constantly. i trust him.

Following are things I've seen about the Toyota obdII codes as it pertains to this:


  • I think that I remember Toyota mis-defining that code number. It's supposed to refer to the O32 sensor signal or heater or the sensor itself. I think I remember that from somewhere that Toyota mis reads that code.
  • By accident I left coolant temperature sensor disconnected. It generated 2 codes. p0115 and p0125. P0115 is the temperature coolant sensor. P0125 Has to do with not getting into a closed loop circuit. Auto Zone listed the cure for the code (125) as faulty temp. sensor, 2. bad thermostat or3. low on coolant. When I rewired the O2 sensor the Mil went out, no more codes,
    From my experience on a Toyota P0125 was a disconnected or bad O2 sensor. Before cat. converter. Code p0115 is disconnected or bad coolant temperature sensor. Not the sensor that controls temp. gauge on dash but sensor that controls fuel mixture. It has a plug with 2 wires connecting. The temp. gauge sensor has one wire,and it is located on the end of the engine very close to the distributor. The coolant temp. sensor is located on the firewall side of the head also close to the distributor but it faces at a right angle to the distributor.
  • I have exactly the same behavior with a 2000 Corolla. If I unplug the oxygen sensor, a few minutes later, I get a P0125 Insufficient Coolant Temperature... followed shortly by a P0135 O2 Heater Circuit.... The latter makes sense, the former, not so much. Apparently a bug in Toyota's software.
  • on some models, Toyota does not adhere to the SAE standard definition for DTC P0125. That code can be for a Coolant Temperature Sensor concern, but it can also relate to O2 sensor function... which would make more sense that a P0135 would follow.
    Fault trace the O2 sensors and if the PCM and harness check out, replace the sensor(s) with O.E. parts.


  • I'm not trying to be confrontational - just trying to figure the darned thing out!

    Ian

    Response From Hammer Time

    You know, this is my fault for just taking your word for the definition of this code number. After looking into the code, it appears that it has nothing at all to do with coolant temp.
    P0125




    CIRCUIT DESCRIPTION
    The Oxygen sensor (O2S) produces a voltage that varies between 0.1 V and 0.9V under normal operating conditions. The Engine Control Module (ECM) monitors this voltage and determines if the exhaust is lean or rich. If the voltage input at the ECM is about 0.1V the exhaust is lean, and if the voltage input is about 0.9V the exhaust is rich. The ECM constantly monitors the O2S 1 signal during closed loop operation and compensates for a rich or lean condition by decreasing or increasing injector pulse width as necessary.

    CONDITIONS FOR SETTING THE DTC
    After engine is at normal operating condition, O2S 1 output does not indicate RICH within 7.5 minutes when the following condition are met.

  • Engine speed at 1,500 RPM or more.
  • Vehicle speed at 25-62 MPH.
  • Throttle valve position is open.
  • Engine has been running for at least 140 seconds.

  • ACTION TAKEN WHEN THE DTC SETS
  • The ECM will illuminate the MIL during the second key cycle in which the DTC sets.
  • The ECM will store the conditions which were present when the DTC set as Freeze Frame Data.

  • CONDITIONS FOR CLEARING THE MIL/DTC
  • The ECM will turn the MIL OFF on the third consecutive trip cycle during which the diagnostic has been run and the fault condition is no longer present.
  • A DTC will clear after 40 consecutive warm-up cycles have occurred without a fault.
  • A DTC can be cleared by using the scan tool Clear Information function or by disconnecting the ECM battery feed.

  • DIAGNOSTIC AIDS
    Check for the following conditions:
  • Oxygen sensor wiring. The sensor pigtail may be mispositioned and contacting the exhaust system.
  • Poor ECM to engine grounds.
  • Fuel pressure. A condition which causes a lean exhaust can cause DTC P0125 to set. The system will go lean if pressure is too low. The ECM can compensate for some decrease. However, if fuel pressure is too low, a DTC P0125 may be set. Refer to Fuel System Diagnosis.
  • Lean injector(s).
  • Vacuum leaks. Check for disconnected or damaged vacuum hoses and for vacuum leaks at the intake manifold, throttle body, EGR system, and crankcase ventilation system.
  • Exhaust leaks. An exhaust leak may cause outside air to be pulled into the exhaust gas stream past the O2S, causing the DTC P0125 to set. Check for exhaust leaks near the O2S 1 sensor.
  • Fuel contamination. Water, even in small amounts, can be delivered to the fuel injectors. The water can cause a lean exhaust to be indicated. Excessive alcohol in the fuel can also cause this condition. Refer to Alcohol-Contaminants-In-Fuel Test for procedure to check for fuel contamination.

  • The information included in the Freeze Frame data can be useful in determining the vehicle operating conditions when the DTC first set.

    If any wiring repairs need to be made, Refer to Repair Procedures in Diagrams.

    TEST DESCRIPTION
    Number(s) below refer to the step number(s) on the Diagnostic Table.
    1. The OBD System Check prompts the technician to complete some basic checks and store the freeze frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
    2. This step verifies whether the malfunction is a hard failure or an intermittence.
    1. This step verifies whether the ECM is able to receive a signal from the O2S 1.

    Response From Sidom

    You are little off base here with the code you are getting...

    Your O2 data is way off base but since it's not related to the code there is really no sense going into this right now...

    The code you posted is for an engine that is running too cool. Computer controlled engines require a minimum of 195° for peak performance. It's to the point now that and OBD II systems will actually set a code if it runs too cool after going into closed loop.

    The usual problem for this code is a stuck open T stat.

    You've changed it and even with an AM non-OE stat I would find it highly unlikely that the new aftermarket one is defective and sticking open as well. So the next thing to check would be the ECT (coolant temp) sensor and reading the PCM is getting.

    With the scanner the 1st thing you will want to do is look at the ECT PID and see if the temp is correct for how hot the engine is or wait until the morning and look at it and the temp should be very close to the ambient temp. So is it's 70 out & temp is showing 30° then you found your problem. If not it gets a little harder, you'll need to access the freeze frame data, find out when the code set & try and duplicate the conditions......

    Honestly, for a DIYer with minimal tools, you could change the T stat and then ECT sensor and connecter, if you are still getting the same code it would probably be best to take the car into a shop to have checked out....But if you have the experience to trace a possible intermittent voltage drop/short/ open in the wiring then that would be the next step before condemning the PCM.......

    Response From Hammer Time

    Yours may work. I'm not familiar with it. You just need something capable of displaying the digital coolant temp reading coming from the sensor.