Introduction
The P0335 diagnostic trouble code indicates a failure in the circuit of the Crankshaft Position Sensor (CKP) “A”. The crankshaft position sensor monitors the speed and rotational position of the crankshaft, sending continuous data to the engine control unit (ECU). The ECU uses this crucial information to control ignition timing and fuel injection. Without a clean signal from this sensor, the engine will either run poorly or fail to start altogether.
Common Symptoms
- Check Engine Light illuminated on the dashboard.
- Engine cranks but refuses to start (no-start condition).
- Engine stalls suddenly while driving or idling.
- Misfires, engine hesitation, or erratic acceleration.
- Tachometer (RPM gauge) staying at zero while cranking.
Primary Causes
- Faulty Crankshaft Position Sensor: Internal electrical failure or mechanical damage to sensor “A”.
- Damaged Wiring Harness: Frayed, burned, or corroded wiring in the sensor circuit due to heat or physical wear.
- Corroded Electrical Connectors: Loose, dirty, or water-damaged pins at the sensor plug.
- Reluctor Ring Damage: Broken or chipped teeth on the tone ring mounted on the crankshaft or flywheel.
- Dead or Weak Battery: Low system voltage during cranking causing signal dropouts.
Step-by-Step Diagnosis & Fixes
- Inspect Wiring and Connector: Check the wiring leading to the crankshaft sensor for heat damage or abrasion. Ensure the harness plug is clean and fully seated.
- Check System Voltage: Verify that the battery is fully charged and supplying stable reference voltage to the sensor circuit.
- Inspect the Sensor and Reluctor Ring: Remove the sensor to check for metal debris on the magnetic tip and inspect the reluctor ring teeth through the mounting hole for damage.
- Test Signal and Replace Sensor: Use a multimeter or oscilloscope to test for reference voltage, ground, and signal pulse while cranking. If power and ground are present but signal output is absent, replace the crankshaft position sensor.