Crankshaft Position Sensor A Circuit High Input
The P0338 code indicates that the Engine Control Module (ECM) has detected a voltage signal from the crankshaft position sensor (CKP) circuit that is higher than the expected range. This sensor monitors engine speed and position for fuel injection and ignition timing. A high input can result from a faulty sensor, wiring issues, or a short to voltage. This condition can cause drivability problems and may prevent the engine from starting.
01. Most Common Causes
- Faulty crankshaft position sensor
- Short to voltage in the sensor circuit
- Damaged wiring or connector
- ECM malfunction (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Engine cranks but does not start
- Intermittent stalling or rough running
- Poor acceleration or hesitation
03. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Visually inspect the CKP sensor wiring and connector for damage or corrosion.
Step 3: Measure voltage at the sensor signal wire with key on; should be around 5V reference. If higher, suspect short to voltage.
Step 4: Test the sensor resistance and compare to specifications; replace if out of range.
Step 5: Check for continuity and shorts in the wiring between sensor and ECM.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
No, it is not safe. The engine may stall or fail to start, leading to a breakdown or accident. Have it diagnosed and repaired promptly.
How much does it cost to fix?▼
Typically $50-$150 for a new sensor plus labor. If wiring repair is needed, costs may be higher.