P0464: A fuel-level jump that falsely resembles refueling

P0464 monitors intermittent fuel-level information during the cited GM ELCP leak-test sequence. An apparent refueling event can cause that off-cycle test to abort. The controller then checks whether the level change persists long enough to support real refueling.

A temporary jump is treated differently

The published event is a fuel-level change greater than ten percent that does not remain at the required changed level for thirty seconds within a 600-second rationality window. A confirmed refueling event produces a passing sample; an unconfirmed one supports an intermittent level-signal failure.

The table uses two failures out of three event samples and allows this evaluation up to once per engine-off period. These counts should not be confused with three adjacent dashboard readings. Its timing is tied to a leak-test opportunity several hours after shutdown.

Correlate level with what actually happened

Preserve level history, tank-pressure activity and whether fuel was really added. The document maintains separate counters for level-triggered and vacuum-triggered refueling detection. That distinction helps identify which input diverted the leak sequence.

A canceled EVAP leak test is not itself proof of a leak or a failed level sender. Check communication and related sensor prerequisites, then use the applicable intermittent-signal procedure. Verification requires a valid off-cycle sequence and rational level behavior; clearing the code followed by a short drive does not exercise this event-based test.

Source and applicability

This explanation is limited to the 2025 GM 25OBDG03A monitor on page 302, page 303, page 304. Its thresholds are calibration examples, not universal specifications. Confirm the vehicle, engine and controller procedure before applying them.