I've had my 2004 3.0i BMW Z4 for almost a year and have not known it without a service engine soon light, most notably a P0174 error code.
The car had a rough idle that was fixed a week ago. A lot of work was done on the car by my mechanic, from replacing the fuel pump and fuel tank, to replacing air intake tubing, and most recently, a burnt O2 sensor was replaced. Multiple smoke tests were done on the car but no vacuum leak was found. No matter what work is done, the service engine soon light comes back after a 15-30 miles after every fix. Battery was also just replaced so that is not the issue.
Most recently, we found a burnt O2 sensor and replaced it and that finally got rid of the super rough idle. However the service engine light keeps coming on randomly every 20-30 miles after each time I reset it to see if it will come back. When I get the light, the car doesn't feel like it’s knocking or misfiring and it drives perfectly normal. Usually, the codes are only P0174 / 2883 code Fuel trim, bank 2- System too lean bank 2, however twice now it has given me P0300 / 274E code (Random/Multiple Cylinder Misfire detected), P0303 / 2744 code (Misfire Cylinder 3 Detected) and P0305 / 2743 code (Misfire Cylynder 5 Detected) as well. What should I look at next?
The car currently drives extremely well, the best I've ever had it. It is smooth, does not ever feel like it is misfiring even with the occasional codes. One thing I noticed, I am not sure if it is related, is that when I enter the OBD2 scanner, the ISO15765-4 CAN(11bit), ISO15765-4 CAN(29bit), ISO14230 4 KWP and ISO14230-4 KWP(5BPS) fails. Not sure if it is related can someone please clarify what that means. My mechanic thinks the system too lean errors might come from an electrical issues. Someone has similar issues? If there was a vacuum leak or misfires, wouldn't they happen much more often so I wouldn't have the codes appear once every 20-40 miles?
Update:
Today I drove about 15 miles, car drove normally. When I stopped for 20 minutes to pick up food, after starting the car up again, the idle was extremely rough and the engine was knocking/shaking extremely loudly, getting louder and louder. I quickly got home and stopped the car. I came back 20 minutes later and drove it around the neighborhood and the idle was perfectly calm and normal. Anyone know what it must be?
The car had a rough idle that was fixed a week ago. A lot of work was done on the car by my mechanic, from replacing the fuel pump and fuel tank, to replacing air intake tubing, and most recently, a burnt O2 sensor was replaced. Multiple smoke tests were done on the car but no vacuum leak was found. No matter what work is done, the service engine soon light comes back after a 15-30 miles after every fix. Battery was also just replaced so that is not the issue.
Most recently, we found a burnt O2 sensor and replaced it and that finally got rid of the super rough idle. However the service engine light keeps coming on randomly every 20-30 miles after each time I reset it to see if it will come back. When I get the light, the car doesn't feel like it’s knocking or misfiring and it drives perfectly normal. Usually, the codes are only P0174 / 2883 code Fuel trim, bank 2- System too lean bank 2, however twice now it has given me P0300 / 274E code (Random/Multiple Cylinder Misfire detected), P0303 / 2744 code (Misfire Cylinder 3 Detected) and P0305 / 2743 code (Misfire Cylynder 5 Detected) as well. What should I look at next?
The car currently drives extremely well, the best I've ever had it. It is smooth, does not ever feel like it is misfiring even with the occasional codes. One thing I noticed, I am not sure if it is related, is that when I enter the OBD2 scanner, the ISO15765-4 CAN(11bit), ISO15765-4 CAN(29bit), ISO14230 4 KWP and ISO14230-4 KWP(5BPS) fails. Not sure if it is related can someone please clarify what that means. My mechanic thinks the system too lean errors might come from an electrical issues. Someone has similar issues? If there was a vacuum leak or misfires, wouldn't they happen much more often so I wouldn't have the codes appear once every 20-40 miles?
Update:
Today I drove about 15 miles, car drove normally. When I stopped for 20 minutes to pick up food, after starting the car up again, the idle was extremely rough and the engine was knocking/shaking extremely loudly, getting louder and louder. I quickly got home and stopped the car. I came back 20 minutes later and drove it around the neighborhood and the idle was perfectly calm and normal. Anyone know what it must be?
