P0641 — Sensor reference voltage "A" circuit — open

Code P0641 is a standard OBD-II diagnostic trouble code: Sensor reference voltage "A" circuit — open.

In our record, P0641 is reported most often on Chevrolet and GMC vehicles , against electrical and engine failure patterns , across 2007–2010 model years. Chevrolet alone accounts for 80% of them.

In ProblemsByVin's analysis of the NHTSA owner-complaint record, owners cite P0641 across 5 vehicle failure patterns. Diagnostic codes in complaints are reported by owners and are unverified — they point to where this code shows up, not a confirmed diagnosis. Open a page below for the full pattern (symptoms, mileage, repair costs owners cite).

Vehicles where owners report P0641 5 patterns

2010 Chevrolet Cobalt

electrical — Engine power reduction / limp mode / stalling

2010 Chevrolet Cobalt

engine — Engine power reduced / limp mode

2010 Chevrolet Cobalt

powertrain — Engine power loss and limp mode activation

2008 GMC Yukon

electrical — Check Engine light and transmission shift delay (Hybrid systems)

2007 Chevrolet Impala

electrical — Reduced Engine Power / Limp mode activation

Codes are pulled from what owners wrote in their NHTSA filings — they're allegations, not a shop diagnosis. Always confirm with a live scan. Browse all diagnostic codes →