I bought a 2011 323i with 2.5l. The engine light was on when I bought it and when I scanned it it had 22 codes. Every cylinder misfire codes, all the 02 sensor heaters, a couple of evap and some cat codes. When I cleared the codes just 29f4 and 29f5 came back which is cat conversion and cat conversion 2. I am thinking this may be the 02 sensors but I don’t want to start throwing money in the wrong direction. It also sometimes idles rough upon start up. Any help would be appreciated.
What tool are you using to scan the engine computer (DME in BMWspeak)? How old are the oxygen sensors? BMW considers them to be consumables. I think you car has the wide band sensors and they are typically good for 125k miles. The pre-cat sensors have a major impact on performance while the post cat sensors also monitor the health of the cats. How many miles/kms on the car? Do you have any maintenance history on the car?
Clearing the faults and seeing what came back was the smart thing to do. Cat effencey or cat conversion means the cats are not working correctly and the post oxygen sensors are reporting on what's coming out. To rule out oxygen sensors you would probably have to watch live data and see how the o2 sensors are working. If you had misfire faults with the flashing check engine light that means there is raw fuel getting to the cats and cats don't like raw fuel. it's interesting no misfires faults came back. You can drive it with cat faults and it probably runs fine opposed to misfires that's cause the engine to run rough. Could the post 02 sensors be faulty maybe, with out testing them you wouldn't know.
My friend scanned it with his scanner and cleared the codes now I used a innova 3130e which reads the codes but does not erase them. No idea how old the 02 sensors are. It has 178000 km. Only have history
Until 60,000
Km - it was in twice for vanos under warranty. I was thinking 02 sensors but that is about 1k for
Bosh and when I bought the Chinese for my wife’s x5 they didn’t last very long. The scanner I have won’t give live data for bmw. How can I test the 02 sensors and also what kind of scanner would I need to see which cylinder(s) are misfiring ? The dealership told me that they had a similar problem and it was the camshaft tunnel but it is usually misfire in the back cylinders. Since it was misfire in a the cylinders I am hoping it is just the 02 sensors.
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