P0339: Crankshaft position sensor A: circuit intermittent.
Meaning, symptoms, causes and checks
P0339 indicates intermittent CKP A signal loss. This signal provides crank position/speed. A does not identify an engine bank, and the code alone does not justify sensor or timing replacement.
Affected system: Powertrain
Symptoms
- Hard/no starting or engine stalling.
- Engine lamp and absent/unstable scan-tool RPM, possibly only when hot.
Possible causes
- Loose contact, internally broken wire or heat/vibration-damaged harness.
- Thermal sensor fault or signal disturbed by target, mounting or interference.
What to check
- Record freeze-frame and CMP/correlation codes; monitor cranking RPM and when P0339 occurs.
- Identify Hall/active versus inductive design from service data, not pin count alone.
- Inspect connector, routing and sensor mounting; examine target/contamination through approved access.
- Monitor under comparable heat/vibration; test harness safely away from moving parts.
- Compare signal at sensor and ECM to locate dropout; retest under original conditions.
Also written as: P0339-00, P033900, PO339 (some scan tools add the fault-type byte, e.g. -00).