P0378
Timing Reference High Resolution Signal B Intermittent/Erratic Pulses
Timing reference signal B pulses are erratic — connector or wiring intermittent, contamination on tone wheel, or sensor partially failed.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Intermittent connector or contaminationCommon
- Connector with intermittent contact under vibrationLess likely
- Harness routed against vibrating componentLess likely
Parts involved
- Camshaft Position Sensor
P0378 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.