P0335: Crankshaft Position Sensor "A" Circuit
Title: SAE J2012 generic definition. Manufacturer-specific definitions and enhanced codes can differ; check service information for the exact vehicle.
What P0335 means
The ECM isn't seeing a usable crankshaft position signal.
What sets it
The crank sensor tells the ECM engine speed and position, which it needs for spark and injection timing. If the signal is missing or electrically wrong while the engine is cranking or running, P0335 sets. On many engines no crank signal means no start.
Symptoms
- Crank, no start
- Stalling, especially when hot
- Tachometer drops to zero or jumps
- Intermittent cut-outs
Is it safe to drive?
General guidance, not a guarantee: Not recommended if the engine is stalling. A stall in traffic is a safety risk. Diagnose before driving if it has cut out. If in doubt, have it towed and diagnosed.
Common causes
Listed roughly from most to least common in general practice. The real order varies by vehicle, mileage and history.
- Failed crank sensor: heat-related failures are common
- Wiring or connector damage near the sensor
- Damaged reluctor or tone ring
- Debris on a magnetic sensor tip
- Incorrect air gap after repair work
Test before you replace: diagnostic sequence
General guidance only. Always follow the vehicle manufacturer's service information, specifications and safety procedures. Any figures below are general guidelines that defer to the manufacturer's specification.
- Watch the engine rpm PID while cranking. Zero rpm while cranking supports a missing crank signal.
- Inspect the sensor connector and harness, especially where it runs near hot or moving parts.
- Check the sensor's supply, ground and reference circuits per the wiring diagram.
- Scope the sensor signal while cranking and compare with a known-good pattern.
- If the supply and wiring are good and the signal is missing or distorted, inspect the sensor tip and the reluctor ring.
- Replace the sensor only after the circuit checks out. Then perform any crank variation relearn the manufacturer requires.
Bench note: For hot-stall complaints, try to catch the failure in the act: scope or monitor rpm while the engine is heat-soaked.
How-to guides for this code
Related codes
FAQ
Can a bad crank sensor cause no start?
Yes. On many engines the ECM won't fire spark or injectors without a crank signal.
Do I need a relearn after replacing it?
Some vehicles require a crankshaft position variation relearn for misfire detection. Check the manufacturer's procedure.
Sources
- SAE J2012, Diagnostic Trouble Code Definitions (standard page; code titles only)
- Generic code title cross-check: obd-codes.com generic code list
Written with AI assistance and reviewed for accuracy; not a substitute for OEM service information. Shop Docs Studio is not affiliated with SAE, EPA, CARB or any vehicle manufacturer.