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Any advice on why my check engine light isn't coming on when I turn power on? Trying g to pass inspection and the guy reset computer. Drove it 100+ miles and retested. 2 diagnostic codes problem: P0420: B1 catalyst system efficiency below threshold and P0442: evaporative system leak detected (small leak). Still check engine light not showing up when power on. Please help if you can. Thanks in advance.
 

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Discussion Starter #8
Lance, Any advice on the 2 diagnostic codes problem: P0420: B1 catalyst system efficiency below threshold and P0442: evaporative system leak detected (small leak)?
 

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BMWCCA HPDE Instructor
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Question: Is the water temp gauge going to exactly 12 o'clock and staying there after about 10 minutes of driving? If not, the t-stat has failed in the open position, thus causing the engine to run rich, which will trip up the 02 sensor and trow a code.

Also, the evap system leak could just be something as simple as a worn out seal on the gas cap.
 

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Discussion Starter #14
Temp gauge gauge is fine. Saw online below efficiency threshold could be a bad cat conv. True or still maybe just an O2 sensor?
 
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