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Old 07-17-2013, 10:07 AM   #1
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Durametric fault code question

Getting these two codes:

PO139 - Fault Code 17 - Sensor ageing behind cat converter cylinder (1-3)
PO140 - Fault Code 12 - O2 sensor behind cat converter cylinder (4-6)

Car is a 2002 S

These are just for bad 02 sensors, right? Nothing about the cat itself? Just replace the two sensors? And does behind mean before or after the cat?

Thanks for the help


Last edited by sfoster13; 07-17-2013 at 10:18 AM.
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Old 07-17-2013, 10:42 AM   #2
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Originally Posted by sfoster13 View Post
Getting these two codes:

PO139 - Fault Code 17 - Sensor ageing behind cat converter cylinder (1-3)
PO140 - Fault Code 12 - O2 sensor behind cat converter cylinder (4-6)

Car is a 2002 S

These are just for bad 02 sensors, right? Nothing about the cat itself? Just replace the two sensors? And does behind mean before or after the cat?

Thanks for the help
Maybe, or maybe not. P0139 is indication of an aging (read dying) sensor behind the three way cat on bank 1-3. That said, P0140 is indication of an interruption of signal from the same sensor, which is often a wiring or connector issue.

I would use the Durametric to read the voltages for the sensor to see if they are in range, if they are, you may want to check its harness for problems.
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Old 07-17-2013, 11:00 AM   #3
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Maybe, or maybe not. P0139 is indication of an aging (read dying) sensor behind the three way cat on bank 1-3. That said, P0140 is indication of an interruption of signal from the same sensor, which is often a wiring or connector issue.

I would use the Durametric to read the voltages for the sensor to see if they are in range, if they are, you may want to check its harness for problems.
Aren't the faults for two different banks?
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Old 07-17-2013, 11:35 AM   #4
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Quote:
Originally Posted by sfoster13 View Post
Getting these two codes:

PO139 - Fault Code 17 - Sensor ageing behind cat converter cylinder (1-3)
PO140 - Fault Code 12 - O2 sensor behind cat converter cylinder (4-6)

Car is a 2002 S

Nothing about the cat itself?
When the CAT starts to fail you will get its own code saying that its not efficient any more or something like that.
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Old 07-17-2013, 11:50 AM   #5
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hmmm, this doesn't look good



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Old 07-17-2013, 12:15 PM   #6
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Yeah, you've got a problem. First of all, this is what a good before and after sensor set should look like:



When the main three way cat goes bad, the sensor behind the cat starts following the voltage curve of the one ahead of the cat, because the cat is no longer converting the gases:



In your case, it does not look like the cat (yet), but more like the signal is interrupted or inconsistent, which would be more likely a wiring or electrical issue.
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Old 07-17-2013, 12:29 PM   #7
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could it be the connector on the O2 sensor?
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Old 07-17-2013, 12:52 PM   #8
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could it be the connector on the O2 sensor?
Yes, could be lose or corroded, could also be frayed wire somewhere in the harness.
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Old 07-18-2013, 05:56 AM   #9
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Thanks for the help
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Old 10-21-2013, 04:02 PM   #10
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Now I'm getting 1128 and 1130 after replacing the o2 sensors behind the cat
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Old 10-21-2013, 04:59 PM   #11
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Now I'm getting 1128 and 1130 after replacing the o2 sensors behind the cat
Codes are for the same problem on both banks: System has reached its enrichment limits. Usually a sign of an air leak in the intake, low fuel pressure and/or delivery volume.
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Old 10-22-2013, 05:35 AM   #12
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what about the MAF?
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Old 10-22-2013, 09:06 AM   #13
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what about the MAF?
Codes are not related to the MAF, which in any case has minimal impact on how the engine runs below about 3,500-4,000 RPM, and the car will actually run fine with the MAF unplugged.. The codes are very specific, the car is running lean on both banks and the DME cannot richen the mixture up any further. Air leaks and fuel delivery problems are the most common cause for both codes.
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Old 10-22-2013, 10:16 AM   #14
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Makes sense, thank you
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Old 10-22-2013, 12:13 PM   #15
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Old 10-22-2013, 12:14 PM   #16
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Old 10-22-2013, 05:42 PM   #17
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MAF values reading low
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Old 01-25-2014, 06:24 AM   #18
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getting the codes again after replacing MAF, O2 sensors and AOS

what's next on the list?
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Old 01-25-2014, 07:58 AM   #19
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Originally Posted by JFP in PA View Post
Codes are not related to the MAF, which in any case has minimal impact on how the engine runs below about 3,500-4,000 RPM, and the car will actually run fine with the MAF unplugged.. The codes are very specific, the car is running lean on both banks and the DME cannot richen the mixture up any further. Air leaks and fuel delivery problems are the most common cause for both codes.
Quote:
Originally Posted by JFP in PA View Post
Codes are for the same problem on both banks: System has reached its enrichment limits. Usually a sign of an air leak in the intake, low fuel pressure and/or delivery volume.


Re-read the above again............................
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Old 01-26-2014, 06:07 AM   #20
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Yes, which one first. Neither are easy without the right testing equipment for a DIY, right.

Would either air leaks or fuel pressure/delivery be more likely?

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