This happened to me for the first time last night, and I don’t know what to make of it.

I was in the final mile of my commute home, stopped at a red light, when I noticed that my wideband AFR gauge (aftermarket installation) was reading very low, in 9’s instead of the usual ~14.7. The AFR would normalize within a few seconds when I resumed moving, but the car accelerated like pig and the AFR would dive again when coasting or idling at the next traffic signal. This phenomenon got worse at each stop sign and I finally stalled out when turning into my driveway (P0172 System Too Rich); and stalled again 30 feet up my driveway. I haven’t driven it since then.

Has this happened to any of you? Can anyone point me in the right direction regarding what may be wrong? Thanks in advance, and feel free to ask probing questions!

2005 R53. 231,000 miles.

P.S. - Might this have anything to do with gas? I usually run 93 octane, but filled with 91 octane the previous night.

 

I don't think it's the gas. In some parts of the country, as here in the upper midwest, 91 is the highest octane available.

It might be sensor related. Have a look at this thread:
https://www.northamericanmotoring.co...0172-code.html

 

Thank you for the link!