I obtained some readings using PCMSCAN for a 2007 Pontiac Wave(Codes P0171 & P0172). At idle SAE.VPWR recorded 14.229v, frame 3&4 was 57.825, frames 5-33(varied rpms) around 14.4,frame 34, 37 & 40 .049v with the rest again around 14.4v. My question would be: Is the alternator gone wacky?

I have the complete data in an Excel file if someone would like to be challenged with a solution for the Rich/Lean trim codes.

Thank you for your time and efforts.

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    I would suspect the scan tool may be misinterpreting the data. 57v is enough to fry everything in the car and 0.049v ins not enough to light a light bulb. Assuming the car ran the whole time then the values are impossible. – vini_i Oct 4 '16 at 18:45

Had been asked: Maybe O2 sensor is intermittent. Can you monitor just the pre cat O2 sensor for how many times it is switching(high/low) during a 2-3 sec period, engine at idle?

My response: My access to PCMSCAN (1.4.3) doesn't have the O2 data like the newest version has - Palmer Performance wouldn't sell me it for CDN$100 (my budget). Tried locating a Digital Scope - failed. Since the car has a lot of mileage and the O2 sensor looks original, I changed it and VOILA - no codes. Must have been a "lazy" responding up stream sensor ... the learning continues.

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