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bpte46
Joined: 23 Jul 2008
Posts: 3
Location: Bridgeport
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 Posted: Wed Jul 23, 2008 8:59 pm Post subject: HELP!.. After Cat Fuel Trim System, Bank 1 |
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Hi All,
I got an error code After Cat Fuel Trim System, Bank 1 that I can't seem to get rid off. Recently I got two error codes of O2 sensor adaptation limit. I found a leak in the intake rubber boot. I replaced the boots. The error codes still there. I decided to replace all the O2 sensors and the spark plugs. The error code still there. I gave up and took the car to the dealer, they check the car and found no leak, but they see a fuel trim codes. They replaced the fuel filter and the car run OK for about 1 week. After that I got an error code of After Cat Fuel Trim System on bank 1. I took it back to the dealer and they say it's O2 sensor that I just replaced is bad. I told them I swap the sensor, but the error code still say bank 1. They don't believe it. I asked if they will guarantee the O2 sensor is bad, but they refuse. The car is about 100k miles. What else can I do? |
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geminiys
Joined: 13 Oct 2004
Posts: 182
Location: SF, California
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| Posted: Thu Jul 24, 2008 11:46 am Post subject: |
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| Your car is OBDII, therefore it has 4 O2 sensors total. 2 of them are before the CAT and 2 after the CAT. Since the code says after the CAT, the sensors behind CAT are under suspect. Have you swapped those or the 2 before the CAT during your diognostics? |
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bpte46
Joined: 23 Jul 2008
Posts: 3
Location: Bridgeport
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| Posted: Thu Jul 24, 2008 2:59 pm Post subject: After Cat Fuel trim |
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| geminiys wrote: | | Your car is OBDII, therefore it has 4 O2 sensors total. 2 of them are before the CAT and 2 after the CAT. Since the code says after the CAT, the sensors behind CAT are under suspect. Have you swapped those or the 2 before the CAT during your diognostics? |
I swapped the sensor w/ the one in bank 2 and it still say bank 1. I put back the old sensors that I took out and it still stay bank 1. I connect the bank 2 sensor to the bank 1 engine cable and it still say bank 1. I think it maybe something else, but I don't know what else to check for. |
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geminiys
Joined: 13 Oct 2004
Posts: 182
Location: SF, California
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| Posted: Thu Jul 24, 2008 3:40 pm Post subject: |
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I assume you cleared codes in between sessions. Right?
The worse case, your computer is malfunctioning. Check you MAF. Disconnect the electrical wiring harness from the MAF while the car is running, drive for few minutes, and check for new codes. The OBDII should tell you that both Bank1 and Bank2 Fuel Trim are bad. If no change, maybe your MAF is bad. |
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bpte46
Joined: 23 Jul 2008
Posts: 3
Location: Bridgeport
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| Posted: Thu Jul 24, 2008 4:56 pm Post subject: aft cat fuel trim error code. |
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| geminiys wrote: | I assume you cleared codes in between sessions. Right?
The worse case, your computer is malfunctioning. Check you MAF. Disconnect the electrical wiring harness from the MAF while the car is running, drive for few minutes, and check for new codes. The OBDII should tell you that both Bank1 and Bank2 Fuel Trim are bad. If no change, maybe your MAF is bad. |
I cleared the code each time. I just disconnect MAF while the engine is running as suggested and drove for about 10 miles and the check engine light doesn't go on. I stopped the car, turned off the engine and restart the car again. The light comes on w/ the code 08 - Mass Air Meter from the Peak Tool. |
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geminiys
Joined: 13 Oct 2004
Posts: 182
Location: SF, California
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| Posted: Thu Jul 24, 2008 5:29 pm Post subject: |
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| Sorry man. If it is not an O2 sensor (and looks like you are sure it is not), then my next suspect will the computer unit itself. It is expensive, therefore I suggest you take it to an authorized BMW mechanic or a dealer for proper diagnostics. |
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SSearch
Joined: 15 Apr 2003
Posts: 591
Location: Vermont, USA
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| Posted: Fri Aug 29, 2008 7:26 am Post subject: |
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It could also be the wiring running to the O2 sensor. Track it back and you'll probably find a chaffed section. Good Luck.
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SSearch
Joined: 15 Apr 2003
Posts: 591
Location: Vermont, USA
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| Posted: Thu Oct 02, 2008 3:53 pm Post subject: |
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Did the dealer check for vacuum leaks also? +1 for tracing the wiring back and looking for a chaffed spot.
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02 330XI |
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