What it means
The CKP signal voltage is above the upper threshold. Either a sensor producing excess output or a short to supply voltage.
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 tells the controller how fast and where the crankshaft is turning, information needed to time spark and fuel delivery. P0338 sets when the circuit signal is higher than the expected range, often because the signal wire is shorted to a supply or the sensor has failed.
Common causes
Most likely first.
- Signal wire shorted to supply voltage
- Sensor failed
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine light
- Hard starting or stalling
- Rough running
- Erratic tachometer reading
How to diagnose it
- Review freeze-frame data and live engine-speed readings to confirm when the crankshaft sensor A signal is too high or the tachometer reading becomes erratic.
- Inspect sensor A's wiring and connector for damaged insulation, misplaced wiring, corrosion, or contact with a powered circuit.
- Follow the wiring diagram and manufacturer's procedure to test the signal wire for a short to supply voltage.
- Check sensor A and its connector terminals against the manufacturer's specification to identify a failed sensor or poor connection.
- Repair the confirmed circuit fault or replace the sensor if it fails the specified test, then confirm stable cranking and running data.
Common fixes
- Repair a crankshaft sensor A signal wire shorted to supply voltage.
- Repair damaged insulation or loose or corroded connector terminals.
- Replace crankshaft position sensor A if it fails the specified test.
- Clear the code and verify that engine-speed readings remain stable.
Can I keep driving?
The engine may run erratically, stall, or be difficult to restart; avoid long trips and situations where a stall could be dangerous. Stop driving if it begins stalling or the tachometer signal becomes erratic along with poor running.
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.