What it means
The CKP signal voltage is below the lower threshold. Usually a sensor whose internal coil has degraded, or a wiring short to ground.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Crankshaft position sensor A provides the controller with a signal used to determine crankshaft speed and position for starting and engine timing. P0337 sets when that circuit's signal falls below the controller's threshold, which may be caused by a grounded signal wire, poor connection, or a sensor that is not producing enough output.
Common causes
Most likely first.
- Sensor failed (output too low)
- Signal shorted to ground
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine light
- Hard starting or no start
- Engine stalling
- Rough running
How to diagnose it
- Review freeze-frame data and observe engine-speed data while cranking to see whether the controller receives a weak or absent crank signal.
- Inspect sensor A's connector and wiring for corrosion, loose pins, damaged insulation, or a signal wire shorted to ground.
- Using the wiring diagram, check the sensor A circuit for shorts and poor continuity according to the manufacturer's procedure.
- Test sensor A's output and connector terminals against the manufacturer's specification while cranking.
- Repair the circuit fault found or replace sensor A if its output remains below specification with sound wiring.
Common fixes
- Repair a signal wire shorted to ground in the crankshaft sensor A circuit.
- Clean or repair corroded terminals and secure the connector.
- Replace crankshaft position sensor A if it fails the specified output test.
- Clear the code and verify reliable starting and a stable engine-speed signal.
Can I keep driving?
The engine may stall or fail to start, so avoid driving where a sudden loss of power would be hazardous. If it stalls repeatedly or struggles to restart, stop using the vehicle until the fault is repaired.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.