Crankshaft Position Sensor A Circuit High
What does P0338 mean?
The P0338 code means the vehicle's onboard diagnostic system has detected: Crankshaft Position Sensor A Circuit High. This is a critical severity code.
Common Symptoms
- Engine cranks but will not start
- Engine stalls and will not restart
- Tachometer reads erratically or zero
- Check Engine Light illuminated
- Ignition and fuel injection disabled
Probable Causes (Ranked by Likelihood)
- Open circuit in CKP sensor ground wire Very High
- Short to voltage in CKP sensor signal wire High
- Faulty CKP sensor with open internal coil High
- Disconnected or corroded sensor connector Moderate
- PCM input circuit fault Low
Step-by-Step Diagnostic Procedure
-
Check CKP sensor signal with a multimeter during cranking -- excessively high or constant voltage indicates a fault
-
Test for continuity in the sensor ground wire from connector to PCM ground
-
Check for short to voltage in the signal wire -- disconnect the sensor and measure voltage on the signal pin
-
Inspect the sensor connector for pushed-back pins, corrosion, or heat damage
-
Measure sensor coil resistance -- an open reading (OL) confirms internal sensor failure
Frequently Asked Questions
Can I drive with code P0338?
No. A high CKP circuit prevents the PCM from properly determining engine position. The engine will not start or will stall unpredictably.
What causes a high CKP circuit?
A high circuit typically results from an open ground wire, an internally open sensor coil, or a short to voltage in the signal wiring. The PCM reads a voltage higher than the expected operating range.
Can I test the CKP sensor at home?
Yes. With a multimeter, measure the sensor coil resistance (should match spec) and check for AC voltage output during cranking. A complete lack of output or an open resistance reading confirms failure.