Code P0335 indicates a Crankshaft Position Sensor A circuit malfunction. The crankshaft position sensor (CKP) is one of the most critical sensors on a modern engine – the ECM uses it to determine engine speed, crankshaft position, and timing for fuel injection and ignition. When it fails, the engine often will not start or will stall while running. P0335 is a no-start code that needs immediate attention.
What the CKP Sensor Does
The crankshaft position sensor reads a toothed wheel (the reluctor or trigger wheel) attached to the crankshaft. As each tooth passes the sensor, it generates an electrical pulse. The ECM counts these pulses to track crankshaft position and rotation speed. A missing tooth (or a special tooth pattern) marks top dead centre, allowing the ECM to know exactly which cylinder is at which point in its cycle. Without this signal, the ECM cannot fire injectors or spark at the right time, so the engine will not run.
Symptoms
Engine cranks but will not start (no-start condition). Engine stalls suddenly while driving and then will not restart immediately (sometimes restarts after sitting for 30 minutes – heat-related sensor failure). Tachometer drops to zero with the engine still running, then the engine cuts out. Hard starting that requires multiple attempts. Misfires or rough running. The check engine light illuminates and P0335 is stored, often along with related codes (P0336 for circuit range/performance, P0337 for circuit low input, P0338 for circuit high input).
Sensor Types
Most modern crankshaft position sensors are Hall-effect (3-wire: power, ground, and signal) or magnetic/inductive (2-wire: produces a small AC voltage as the trigger wheel teeth pass). Hall-effect sensors generally fail completely (work or do not work). Inductive sensors can degrade gradually, producing a weak signal at low cranking RPM but stronger at higher engine speeds – this causes hard starting that improves once the engine is running.
Common Causes
Failed sensor (most common – heat and vibration eventually kill the sensor). Damaged or contaminated trigger wheel (metal shavings collected on a magnetic sensor’s tip; missing teeth on the reluctor wheel from impact damage). Loose or corroded sensor connector. Damaged wiring (look for chafing, melting, or rodent damage). Failed ECM sensor input (rare but possible). On some vehicles, the sensor mounting bracket can crack and let the sensor sit too far from the trigger wheel.
Testing
For Hall-effect sensors, check power (typically 5V or 12V depending on the system), ground, and look for a square-wave signal while cranking with an oscilloscope. For inductive sensors, measure resistance across the two terminals (typically 200 to 1500 ohms – check the manual for your specific spec) and look for an AC voltage during cranking. Use a scan tool with live data to watch RPM during cranking – it should show a value (usually 100 to 250 rpm) if the sensor is reading correctly. Zero RPM during cranking confirms a sensor or wiring issue.
Replacement
The sensor location varies – usually on the side of the engine block, the bell housing, or the timing cover. Some are easy to access; others require removing other components. Use OEM or quality aftermarket sensors (Bosch, Denso, NTK, Delphi) – cheap unbranded sensors often fail quickly or never work right. After replacement, clear the codes with a scan tool and start the engine. Some vehicles require a relearn procedure for the trigger wheel pattern – the manual specifies if needed.
Sensor specifications and locations are vehicle-specific. MechanicMate offers PDF workshop manuals for over 960 models at mechanicmate.net/shop.
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