P2065: secondary fuel-level inactivity depends on tank state and distance

P2065 is described as secondary fuel-level inactivity in this GM 2009 example. Although the general code title says sensor B circuit, this table is not merely detecting an open wire. It evaluates how the reported fuel level changes across a distance-dependent observation.

Tank state determines the observation

The monitor looks for less than two litres of change. For the documented states in which the secondary sensor is in its measurement range, the observation distance is 37.3 miles. When both sensors indicate the specified full state, the table uses 248.6 miles instead.

Distance can accumulate across driving cycles, but refuelling and a state change reset the accumulation. The engine must be running, battery voltage must exceed 11 V, and the named secondary sensor circuit faults must not be set, pending or confirmed. This historical table explicitly marks the application AWD only.

A stationary gauge is not the whole diagnosis

Record both primary and secondary fuel-level values, the state classification and any reset event. A recently refuelled vehicle may not have the same diagnostic history as one showing an unchanged gauge over several trips.

The source also describes a shared illogical-sensor condition that cannot isolate the faulty sender and can involve both primary and secondary codes. Thus, P2065 alone should not become an automatic secondary-sender replacement instruction. Use the matching vehicle procedure, and do not treat the listed distances as a recommendation to keep driving a vehicle with uncertain fuel information.

Source and applicability

GM 2009 09OBDG06 Engine Diagnostics, AWD-only primary/secondary fuel-level example on the cited page. Specific model and engine fitment has not been established.

General Motors source, physical page 9