P0337 — Crankshaft position sensor A: circuit low

P0337 indicates a low electrical level in the CKP A circuit. 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

• Short circuit, unsuitable active-sensor supply/ground or damaged connection.
• Sensor/trigger fault; insufficient inductive-sensor amplitude, subject to testing.

What to check

• Record freeze-frame and CMP/correlation codes; monitor cranking RPM and when P0337 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.
• Test supply/ground where used, then wiring continuity/insulation to diagram.
• Scope the signal at sensor and ECM; separate shorts from weak amplitude without resistance-testing an unidentified Hall sensor.

Also written as: P0337-00, P033700, PO337 (some scan tools add the fault-type byte, e.g. -00).