P0335 indicates a malfunction in the crankshaft position sensor (CKP) circuit. The quickest path to a fix is typically inspecting the CKP sensor, its wiring, and related fuses, then replacing the sensor if the fault remains. A proper diagnosis helps prevent unnecessary part replacement.
When the CKP signal is lost or corrupt, the engine may have trouble starting, stall, run rough, or hesitate, because the engine management system cannot accurately time ignition and fuel delivery. This article explains what P0335 means, common causes, and practical steps to diagnose and repair the issue, with notes on when to call a professional.
What P0335 means
P0335 stands for Crankshaft Position Sensor A Circuit Malfunction. The engine control module (ECM/PCM) relies on a clean, consistent crankshaft position signal to control ignition timing. If the signal is missing, erratic, or out of range, the PCM stores the code and illuminates the check engine light. Causes can range from a bad sensor to wiring problems, or in rare cases, a faulty PCM.
Common causes
Understanding typical culprits helps guide your inspection and testing. The following list covers the most common sources of P0335.
- Faulty crankshaft position sensor (CKP) itself.
- Damaged, frayed, or corroded wiring between the CKP sensor and the PCM.
- Loose, dirty, or damaged electrical connectors at the sensor or PCM.
- Blown fuse or failed relay supplying the CKP circuit.
- Issues with the crankshaft reluctor/tone wheel (loose, bent, or damaged).
- Oil contamination or debris on the sensor tip or reluctor, affecting signal quality.
- Timing component problems (timing belt/chain) that affect the relation between crank and cam timing.
- Rarely, a faulty PCM or software issue.
Conclusion: Most P0335 cases are traced to sensor or wiring problems, but accurate diagnosis prevents unnecessary part changes.
Do-it-yourself diagnostic steps
Before diving into parts, follow a structured diagnostic plan to confirm the source of P0335 and reduce replacement guesswork.
- Use an OBD-II scanner to confirm P0335 and check for related codes that may point to timing or sensor issues (e.g., P0336, P0339).
- Verify the vehicle’s battery and charging system are healthy, since voltage dips can mimic sensor problems.
- Inspect fuses and relays tied to the CKP circuit according to the owner’s manual or service information.
- Carefully inspect the CKP sensor wiring harness and connectors for damage, oil ingress, corrosion, or loose connections. Gently wiggle the harness while monitoring live data to spot intermittent faults.
- Check the crankshaft reluctor ring or tone wheel for missing teeth, damage, or misalignment that could disrupt the signal.
- Test the CKP sensor with a multimeter or an oscilloscope. Look for proper resistance (per vehicle specs) and, if possible, a clean waveform when cranking. A flat or erratic signal indicates a fault.
- Ensure proper engine ground and PCM ground connections. A bad ground can distort sensor readings.
- If wiring and sensor tests are favorable, replace the CKP sensor with a quality part and clear codes. Re-test to confirm the issue is resolved.
- Perform a road test to verify normal starting, idle, and acceleration without returning P0335.
Note: If you see recurring starting problems, stalling, or misfires after these steps, professional diagnostic help may be required, especially if timing or PCM concerns are suspected.
Tools and safety reminders
Useful tools include a multimeter or oscilloscope, a scan tool, a flashlight, and basic hand tools. Always disconnect the battery before removing electrical connectors, and follow the vehicle’s service manual for torque specs and procedures to avoid damage.
When to seek professional help
If the CKP wiring and sensor test good but the code persists, or if timing components or the PCM are suspected, professional diagnosis with OEM-level scan tools and calibration software is recommended. Some vehicles require specific service procedures and software updates to accurately diagnose and fix P0335.
Replacement and repair considerations
Replacing components should be done with attention to compatibility and proper installation. The following guidance helps ensure a reliable repair.
- Choose a CKP sensor that matches your vehicle’s make, model, and engine type. OEM parts are typically reliable, though reputable aftermarket sensors can work well.
- Disconnect the battery before removing or installing electrical components to prevent short circuits and protect sensitive electronics.
- Access the sensor as required by the vehicle’s design, remove seals if present, and install the new sensor with the correct orientation and torque as specified by the service manual.
- Inspect and, if needed, replace the sensor mounting seal or gasket to ensure a proper seal and signal integrity.
- Reconnect all wiring harnesses securely, confirm a solid click at connectors, and re-route any protective loom to block moisture and debris.
- Clear codes with a scan tool and perform a road test to confirm the fix and to ensure no new codes appear.
Note that if timing components are involved or if a PCM issue is suspected, professional service may be necessary to avoid timing-related engine damage.
Summary
P0335 signals a malfunction in the crankshaft position sensor circuit. A careful, methodical approach—verifying power, ground, sensor integrity, wiring continuity, and timing components—often leads to a straightforward fix such as replacing the CKP sensor or repairing wiring. Use live data and, if available, an oscilloscope to validate the CKP signal, and re-test the vehicle after repair to ensure the code does not return.
Bottom line: start with a diagnostic scan, inspect wiring and connectors, test or replace the CKP sensor as needed, and verify the engine runs cleanly and without recurring codes.