P0365: Bank 1 camshaft Sensor B pulse loss in crank-referenced windows

P0365 identifies the Bank 1 camshaft Sensor B circuit. The cited GM strategy detects missing cam pulses during starting or running and can also count their absence against a synchronized crankshaft reference. It does not establish a universal intake/exhaust sensor location from the letter B alone.

Different routes to missing-pulse evidence

During cranking, timers use the last received cam pulse or the duration of starter engagement without a pulse. Supporting crank pulses or valid airflow indicate that engine movement should be occurring. A running check looks for fewer than four pulses over more than three seconds.

A separate start-attempt path begins at medium-resolution crank region 3 and examines twelve crank events. This path requires synchronization and no active crank-sensor fault. That makes crank reference validity part of the evidence, not an unrelated detail.

What to verify after diagnosis

Record starter state, Sensor B pulse activity and crank synchronization. A normal cam angle after the event does not prove pulses were continuously available during the failed window. The table identifies the monitored signal path but not the failed physical component.

Use the applicable circuit and pattern procedure to establish why pulses disappeared. Verification should cover the relevant starting or running state and confirm the absence monitor completes with a valid crank reference. A single successful restart may not reproduce a running-only pulse interruption.

Source and applicability

This explanation is limited to the 2025 GM 25OBDG03A monitor on page 274. Its thresholds are calibration examples, not universal specifications. Confirm the vehicle, engine and controller procedure before applying them.