Talked to the tech who did the AOS. He reported he removed the MAF and found it perfectly free... |  |  |
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| Starting to notice a pattern.. Every other time the AOS fails I get O2 sensor error codes... MarcW - 9 years ago |
After the first AOS failure the CEL was coming on and pointing to an O2 sensor, and eventually I caught the sensor in the act, so to speak and replaced both the bad one and its neighbor on the other bank.
After the 2nd AOS failure all was well.
Now after just having the 3rd AOS fail and replaced, today the CEL came on. DTCs: P0134 and P1128.
CEL came on with no drama from the engine. Driving along and the light wasn't on then it was.
P0134 - Oxygen Sensor Ahead of TWC, Bank 1 – Interruption of Signal
Possible causes:
-- Open circuit in signal wire or ground wire
-- Oxygen sensor heating not functioning
-- Output stage in DME control module faulty
-- Internal resistance too high
Probably the last possible cause because the failure appears to be intermittent.
I used my Actron code reader to run some O2 sensor tests and all that were supported came back with passing results. 'course I shut off the engine before running the tests -- the code reader was in the other car -- and I know shutting off the engine from my previous time trouble shooting O2 sensor problems often (make that almost always) "fixes" the sensor, at least for a while. That was why after the first AOS failure it was so hard to catch the bad sensor in the act.
I'm going to have a tech check the sensor wiring. The car was just the shop and while I doubt it maybe a sensor connector got compromised. Also, not too many months ago the exhaust manifolds were replaced and that P0134 could be from an exhaust leak, which is a long shot as I don't hear anything.
As for the P1128 error code:
– Incorrect signal from MAF sensor
– Intake air system leaking
– Fuel pressure too low
– Volume supply of fuel pump too low
– Fuel injectors fouled
– Exhaust system leaking
Could be the MAF -- I can't tell you how many miles this MAF has lasted -- but the engine is running OK.
Some time back the oil filler tube cap was found leaking so I'll be sure to check that out. Kind of funny what becomes a "wear" item after the miles start to add up.
Fuel pump is relatively new. I replaced it at either 200K or 220K miles. 'course, they can go bad at any time but it doesn't feel like a fuel pump problem.
Plenty of fuel in the tank. Just filled up (paying ... now get this: $3.819/gallon! Yeah, baby!)
The engine doesn't really act like fuel injectors are fouled.
Exhaust system leak? Tthe exhaust manifolds were replaced not too many months ago and a leak is always a possibility, but I do not hear anything that remotely sounds like an exhaust leak.
I'm thinking MAF or a leaking oil filler tube cap. (Missing this before had me replace a perfectly good MAF.) A leaking oil filler tube is also a possibility. At some place IIRC there is a rubber bellows that can crack.
More when I know more.
After the 2nd AOS failure all was well.
Now after just having the 3rd AOS fail and replaced, today the CEL came on. DTCs: P0134 and P1128.
CEL came on with no drama from the engine. Driving along and the light wasn't on then it was.
P0134 - Oxygen Sensor Ahead of TWC, Bank 1 – Interruption of Signal
Possible causes:
-- Open circuit in signal wire or ground wire
-- Oxygen sensor heating not functioning
-- Output stage in DME control module faulty
-- Internal resistance too high
Probably the last possible cause because the failure appears to be intermittent.
I used my Actron code reader to run some O2 sensor tests and all that were supported came back with passing results. 'course I shut off the engine before running the tests -- the code reader was in the other car -- and I know shutting off the engine from my previous time trouble shooting O2 sensor problems often (make that almost always) "fixes" the sensor, at least for a while. That was why after the first AOS failure it was so hard to catch the bad sensor in the act.
I'm going to have a tech check the sensor wiring. The car was just the shop and while I doubt it maybe a sensor connector got compromised. Also, not too many months ago the exhaust manifolds were replaced and that P0134 could be from an exhaust leak, which is a long shot as I don't hear anything.
As for the P1128 error code:
– Incorrect signal from MAF sensor
– Intake air system leaking
– Fuel pressure too low
– Volume supply of fuel pump too low
– Fuel injectors fouled
– Exhaust system leaking
Could be the MAF -- I can't tell you how many miles this MAF has lasted -- but the engine is running OK.
Some time back the oil filler tube cap was found leaking so I'll be sure to check that out. Kind of funny what becomes a "wear" item after the miles start to add up.
Fuel pump is relatively new. I replaced it at either 200K or 220K miles. 'course, they can go bad at any time but it doesn't feel like a fuel pump problem.
Plenty of fuel in the tank. Just filled up (paying ... now get this: $3.819/gallon! Yeah, baby!)
The engine doesn't really act like fuel injectors are fouled.
Exhaust system leak? Tthe exhaust manifolds were replaced not too many months ago and a leak is always a possibility, but I do not hear anything that remotely sounds like an exhaust leak.
I'm thinking MAF or a leaking oil filler tube cap. (Missing this before had me replace a perfectly good MAF.) A leaking oil filler tube is also a possibility. At some place IIRC there is a rubber bellows that can crack.
More when I know more.
byproducts in both the intake (maybe) and exhaust that could foul, temporarily or otherwise, either component.
I'd reset, forget and give them time. if they re-occur for too long, then worry.
of course you should cover yourself with a report right now.
Grant
Grant
gee-lenahan-at-gee-mail-dot-com
I'd reset, forget and give them time. if they re-occur for too long, then worry.
of course you should cover yourself with a report right now.
Grant
Grant
gee-lenahan-at-gee-mail-dot-com
| Talked to the tech who did the AOS. He reported he removed the MAF and found it perfectly free... MarcW - 9 years ago |
of any oil (or dirt) contamination. He confirmed what I have suspected, and in fact have said and that if the stock air filter is changed at reasonable intervals and the intake system is left intact and functioning properly (for instance, the filter doesn't end up with a tear or gap in it) the MAF will stay clean.
BTW, this can happen. I recall shortly after I bought my new 2001 Camaro Z28 I happened to remove the cover to the air filter housing and found the filter element not installed properly and the engine was breathing some unfiltered air. The engine air intake was also getting warm air from the engine compartment rather than the cooler air from the intake at the front of the car.
I cleared the codes and will continue to drive the car and see what happens. I put around 30 miles on the car since I cleared the codes and the CEL has not returned. But I expect it will return.
BTW, this can happen. I recall shortly after I bought my new 2001 Camaro Z28 I happened to remove the cover to the air filter housing and found the filter element not installed properly and the engine was breathing some unfiltered air. The engine air intake was also getting warm air from the engine compartment rather than the cooler air from the intake at the front of the car.
I cleared the codes and will continue to drive the car and see what happens. I put around 30 miles on the car since I cleared the codes and the CEL has not returned. But I expect it will return.
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