Crankshaft Position Sensor A Circuit Low Input
The PCM detected a low voltage signal from the crankshaft position (CKP) sensor circuit. The CKP sensor is critical for monitoring engine speed and crankshaft position, which directly control spark timing and fuel injection. Without a proper signal, the engine cannot run reliably.
What You Might Notice
- Engine will not start or difficult to start
- Tachometer not working or showing zero RPM
- Engine stalling or dying while driving
- Rough idle or severe hesitation
- Check Engine light illuminated
Most Common Causes
- 1
Faulty crankshaft position sensor
The CKP sensor itself has failed or is producing a weak signal due to internal damage or wear. This is the most common cause of P0337.
- 2
Damaged wiring or connector corrosion
The sensor wiring harness is corroded, broken, or loose, preventing proper voltage transmission from the sensor to the PCM.
- 3
PCM ground connection failure
A poor or loose ground connection between the PCM and the engine block prevents the CKP sensor circuit from completing properly.
- 4
Defective PCM or circuit board
The PCM itself has developed an internal fault in the CKP sensor input circuit, though this is relatively rare compared to sensor failure.
How to Diagnose It
- 1
Check Faulty crankshaft position sensor — The CKP sensor itself has failed or is producing a weak signal due to internal damage or wear. This is the most common cause of P0337.
- 2
Check Damaged wiring or connector corrosion — The sensor wiring harness is corroded, broken, or loose, preventing proper voltage transmission from the sensor to the PCM.
- 3
Check PCM ground connection failure — A poor or loose ground connection between the PCM and the engine block prevents the CKP sensor circuit from completing properly.
- 4
Check Defective PCM or circuit board — The PCM itself has developed an internal fault in the CKP sensor input circuit, though this is relatively rare compared to sensor failure.
How to Fix It
- 1
Replace crankshaft position sensor
Remove the faulty CKP sensor and install a new OEM or quality replacement sensor. Ensure the new sensor is properly seated and torqued to specification.
- 2
Inspect and repair wiring harness
Examine the CKP sensor wiring for damage, corrosion, or loose connections. Repair or replace damaged wire segments and reconnect terminals firmly.
- 3
Clean PCM ground connections
Locate the PCM ground connections and clean any corrosion from the terminals and mating surfaces. Ensure all ground bolts are tight and making solid contact with the engine block.
- 4
Check connector for damage
Inspect the CKP sensor connector for bent pins, moisture, or corrosion. Clean or replace the connector if damaged, and ensure proper seating.
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