The vehicle is displaying fault code P0171, indicating a 'System Too Lean Bank 1' condition. This typically points to an air-fuel mixture that is too lean in the first engine bank. Common causes include vacuum leaks, faulty oxygen sensors, or issues with fuel delivery systems. For a 2001 Pontiac Montana with a 3.4L V6 engine, this code may also be linked to random misfires and should be investigated thoroughly.
Thank you for the insight—it's accurate. I've reviewed the IM report, which shows EVPD values below minimum thresholds and confirms a vacuum leak. Please see attached scanned copies (low resolution due to file size limitations; higher quality scans could not be uploaded).
I assume you have the 3.4 l V-6... I wouldn't worry about it right now. It may not be a valid test... if, among other codes, a misfire code exists or existed and you didn't clear the code(s). I suspect you did not clear the code(s) as the I/M Test indicates the monitors are all complete...unless you went through a few drive cycles.
Thanks for confirming—my issue was resolved after replacing a completely destroyed vacuum hose. The engine now runs smoothly and the P0171 code has disappeared.
Inspect all vacuum lines and components related to Bank 1, such as gaskets, seals, and grommets. A vacuum leak in this area can cause the P0171 code and may also contribute to random misfires reported in another post. Good luck—please update with your findings.