P0338 critical

Crankshaft Position Sensor A Circuit High

The P0338 code means the vehicle's onboard diagnostic system has detected: Crankshaft Position Sensor A Circuit High. This is a critical severity code.

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Keep driving?: No -- stop driving
DIY difficulty: moderate
Estimated cost: $80 - $350 (parts and labor)

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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.