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Code 13, O2 sensor keeps returning after replacing the O2 sensor

Tiny
JOHN LA
  • MEMBER
  • 1993 PONTIAC GRAND PRIX
  • 3.1L
  • V6
  • 2WD
  • AUTOMATIC
  • 31,000 MILES
It started out with the engine staling when I came to a stop or as I was turning a corner always at low RPM. This has been going on for around four months. I checked the fuel pressure, signal to the TPS. One thing that was always a constant was the code 13, O2 sensor. I replaced these sensors MAP, TPS, Air intake temperature, IAC, crankshaft position, O2 was done twice. Also the ECM I replaced twice in the last three months. The second I installed four days ago. A shop owner scanned my car and nothing stood out but he removed the ECM from its location laid it on his hand as the engine was running and gave it a slap. The engine shut off. There is an inherent problem with these ECM from this time period as the conformal coating applied by GM swelled, causing movement of the electronic components and cracking of critical solder joints. This information is found at Rockauto catalog under the ECM-CARDONE supporting information. He told me that he learned that at the dealership. I replaced the ECM and the car was fine for about two weeks and then the stalling returned. I then replaced the TPS and it ran fine for another two weeks and then the nightmare returned. I for the first time did the idle relearn procedure two days ago and that made a big difference but it stalled out only once so far but when I drove on the beltway at about 65 MPH the service engine light returned and there it was code 13 the O2 circuit all by its self. I buy my parts from Rockauto and use AC Delco when available as is the O2 and the others. Code 13 only appears when I drive at highway speeds such as 65 then the service engine light comes on but not until I am driving at high speeds. I could drive all day long at 40 and bellow and the code 13 will never appear or any other. I Replaced the battery nine days ago. From the information that I have gathered it seems to be a problem with the O2 circuit such as the ground. Any and all input will be appreciated. Thanks
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Sunday, November 4th, 2018 AT 8:12 AM

11 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good morning.

The issues with the early ECM were the boards kept breaking and causing all those issues.

It may be you will need a new ECM instead of a re-manufactured one. They are still available with proms as well.

You could have a harness issue for this code. I attached information for you to follow.

Roy

CIRCUIT DESCRIPTION
The ECM supplies a voltage of about 0.55 volt between terminals "A16" and "A22". (If measured with a 10 megohm digital voltmeter, this may read as low as 0.32 volt.) The O2 sensor varies the voltage within a range of about 1 volt if the exhaust is rich, down through about 0.10 volt if exhaust is lean.

The sensor is like an open circuit and produces no voltage when it is below 360°C (600°F). An open oxygen sensor circuit or cold oxygen sensor causes "Open Loop" operation.

TEST DESCRIPTION
Numbers below refer to step numbers on diagnostic chart.

1. DTC 13 will set under the following conditions:
Engine running for more than 2 minutes after start.
Engine coolant temperature at least 50°C (122°F).
No Code 21 or 22.
O2S signal voltage is steady between 0.35 and 0.55 volt.
Throttle position sensor signal indicates throttle opening greater than 4%.
All conditions must exist continuously for about 25 seconds.

2. This will determine if the sensor is at fault, or if the the wiring or ECM is the cause of the Code 13.

3. In doing this test use only a high impedance digital volt ohmmeter. This test checks the continuity of CKTs 412 and 413. If CKT 413 is open the ECM voltage on CKT 412 will be over 0.6 volt (600 mV).

DIAGNOSTIC AIDS:
An intermittent may be caused by a poor connection, worn through wire insulation, or a wire broken inside the insulation.

Poor Connection or Damaged Harness - Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection, and damaged harness.

Intermittent Test - If connections and harness check OK, "Scan" 02 sensor voltage while moving related connectors and wiring harness, with warm engine running at part throttle in "Closed Loop." If the failure is induced "02 sensor voltage" reading will change from its normal fluctuating voltage (above 600 mV and below 300 mV) to a fixed value around 450 mV. This may help to isolate the malfunction.
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Monday, November 5th, 2018 AT 3:50 AM
Tiny
JOHN LA
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  • 6 POSTS
Thanks Roy/ASEMASTER 6371 and to anyone whom takes the time to answer questions on this site or any other site. How much diagnostic time is reasonable to do the three steps in the flow chart with regards to the o2 sensor problem I am having? Thank you
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Wednesday, November 7th, 2018 AT 2:14 PM
Tiny
ASEMASTER6371
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  • 52,797 POSTS
You are welcome.

Always glad to help.

You should plan on one hour for the diagnostic.

Roy
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Wednesday, November 7th, 2018 AT 2:38 PM
Tiny
JOHN LA
  • MEMBER
  • 6 POSTS
I have a question, if I were to bypass/bridge the 02 sensor wire 412 PPL to A16 ECM and maybe the 413 TAN to the A22 ECM to ground, is this an option? I have the two manuals/books one and two that were used at the dealership for the 1993 Pontiac Grand Prix. I found the view of the ECM that shows the four terminals just like my ECM with connector A = orange, B=White, C=Green, D=Blue. Roy I hope your available to answer this one? Thanks to all.
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Sunday, November 11th, 2018 AT 1:41 PM
Tiny
ASEMASTER6371
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No, do not jump it to that wire or you will fail the ECM.

Roy
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Sunday, November 11th, 2018 AT 6:56 PM
Tiny
JOHN LA
  • MEMBER
  • 6 POSTS
Yesterday I looked over the wiring from the 02 sensor back to the ECM and did not see any breaks etc. Back in April is when the code 13, 02 sensor first appeared. I changed the sensor and put on a new connector for the sensor. If I were to cut the wire going to the 02 sensor and connected a new one and then connect it to the A16 at the ECM it would not work? Would you please explain why this would not work so I could understand? Thanks
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Monday, November 12th, 2018 AT 8:18 AM
Tiny
ASEMASTER6371
  • MECHANIC
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Yes, you can run a new wire. In the other posts you talked about jumping wires. That is not replacing. I thought you were applying power other than the ECM to the sensor.

Roy

Flow chart or description for code 13.

CIRCUIT DESCRIPTION
The ECM supplies a voltage of about 0.55 volt between terminals "A16" and "A22". (If measured with a 10 megohm digital voltmeter, this may read as low as 0.32 volt.) The O2 sensor varies the voltage within a range of about 1 volt if the exhaust is rich, down through about 0.10 volt if exhaust is lean.

The sensor is like an open circuit and produces no voltage when it is below 360°C (600°F). An open oxygen sensor circuit or cold oxygen sensor causes "Open Loop" operation.

TEST DESCRIPTION
Numbers below refer to step numbers on diagnostic chart.

1. DTC 13 will set under the following conditions:
Engine running for more than 2 minutes after start.
Engine coolant temperature at least 50°C (122°F).
No Code 21 or 22.
O2S signal voltage is steady between 0.35 and 0.55 volt.
Throttle position sensor signal indicates throttle opening greater than 4%.
All conditions must exist continuously for about 25 seconds.

2. This will determine if the sensor is at fault, or if the the wiring or ECM is the cause of the Code 13.

3. In doing this test use only a high impedance digital volt ohmmeter. This test checks the continuity of CKTs 412 and 413. If CKT 413 is open the ECM voltage on CKT 412 will be over 0.6 volt (600 mV).

DIAGNOSTIC AIDS:
An intermittent may be caused by a poor connection, worn through wire insulation, or a wire broken inside the insulation.

Poor Connection or Damaged Harness - Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection, and damaged harness.

Intermittent Test - If connections and harness check OK, "Scan" 02 sensor voltage while moving related connectors and wiring harness, with warm engine running at part throttle in "Closed Loop." If the failure is induced "02 sensor voltage" reading will change from its normal fluctuating voltage (above 600 mV and below 300 mV) to a fixed value around 450 mV. This may help to isolate the malfunction.
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Monday, November 12th, 2018 AT 8:33 AM
Tiny
JOHN LA
  • MEMBER
  • 6 POSTS
I inspected the wire going to the O2 sensor and it is one that I had repaired a few years ago after I noticed that it had been chewed on by a rodent. I reached back to the O2 sensor wire and moved it around, followed it to the ECM but did not come across any bad wires. Do not know what took place when I did that but the staling was gone along with the service engine soon light/ code 13- O2 sensor that would appear when I reached speeds of 65 mph. Until 11/27/18 at around 65 mph the service engine soon came on then went away but other then that the engine does not stall. When the weather warms I will replace the wire. This engine has about 30,000 on it and I hope to get much more use out of it.
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Wednesday, November 28th, 2018 AT 12:33 PM
Tiny
ASEMASTER6371
  • MECHANIC
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Okay, you may have disturbed a wiring issue whether in the harness or at the ECM. Check the connector at the ECM for any pins loose, damages, burned or corroded.

Roy
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Wednesday, November 28th, 2018 AT 12:37 PM
Tiny
JOHN LA
  • MEMBER
  • 6 POSTS
Will do. Thanks
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Wednesday, November 28th, 2018 AT 12:44 PM
Tiny
ASEMASTER6371
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You are welcome.

Always glad to help.

Roy
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Wednesday, November 28th, 2018 AT 12:52 PM

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