I'd be looking at the P0171. In closed loop, this is set when the computer has to add +\- 20% more fuel than calculated. It is not usually caused by a faulty O2 sensor (this would be upstream, not downstream). I would be looking for vacuum leaks, it's possible that the MAF sensor is bad, but it wouldn't be the first place that I would be looking. Freeze frame data, and live data would be really useful. The CEL not setting right away is normal after resetting the computer. The various monitors 'set' in a sequence. If you can't find any vacuum leaks, look for low fuel pressure (maybe a bad fuel filter).
02 Sensors
- Thread starter charbaby
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