Engine Runs Rough, Service Engine Soon Light On, DTC P0300 or P0335 Set (Shim Crankshaft Sensor)

Some owners may comment on a rough running condition or a Service Engine Soon (SES) light being illuminated. Upon investigation, the technician may find a DTC code P0300 or P0335.

The crankshaft sensor may be contacting the reluctor wheel.

Remove the crankshaft sensor. Refer to the Crankshaft Position Sensor Replacement procedure in the Engine Controls-4.3L sub-section of the Service Manual. After removing the sensor, inspect the end of it for witness marks that would indicate contact with the crankshaft. If contact with the reluctor ring is indicated, then inspect the front cover for cracking or other signs of alignment concerns. If the inspection indicates that the cover is causing mis-alignments, replace the cover. If replacing the cover, then the 0.5mm shim is not needed.

If the inspection of the front cover indicates that the cover is not the cause of mis-alignments, then the sensor should be shimmed. Add one shim between the sensor and the front cover. If the concern still exists, then add the second shim. Unless the sensor has been rubbed through the casing or deformed by contact with the crankshaft, it should not be replaced.

In either case, the crankshaft relearn procedure should be performed after any repairs.

Parts are currently available from GMSPO.

For vehicles repaired under warranty, use: