The P0335 code points to a fault in the crankshaft position sensor (CKP) circuit A, a critical timing signal the engine control unit relies on. Fixing it usually involves checking wiring and connectors, testing the sensor and its references with a scan tool, and replacing faulty components as needed.
What P0335 Means and Why It Matters
P0335 is a generic diagnostic trouble code indicating a malfunction in the crankshaft position sensor A circuit. The CKP provides timing information to the engine control module (ECM/PCM). When the ECM cannot receive a clean, stable signal, it can result in failure to start, stalling, rough running, or reduced power. Different car makes may label the sensor differently (CKP, CKP-A, or CMP in some diagrams), but the underlying issue is a disrupted crankshaft timing signal in the primary circuit.
Because the CKP is integral to ignition timing and fuel injection, a P0335 can manifest in several ways, from a no-start condition to intermittent performance problems. The diagnosis should confirm whether the problem is the sensor itself, the wiring, or the ECM/related circuitry.
Common symptoms you might notice
These are the warning signs that often accompany a P0335 code. If you observe any of them, a diagnostic check is warranted to verify the source of the problem.
- No crank or failed to start condition, even when the battery is healthy
- Engine cranks but won’t start or stalls soon after starting
- Rough idle, misfires, or sudden surges in engine speed
- Check Engine Light is illuminated and P0335 is stored or pending
- Intermittent starting problems or sudden loss of power
Diagnosing these symptoms involves confirming the code with a scanner and correlating live data (crankshaft RPM, reference voltage, and sensor signal) to pinpoint the faulty part or circuit.
Possible causes of P0335
Several issues can trigger P0335. Understanding the most common ones can guide efficient troubleshooting.
- Faulty crankshaft position sensor (CKP) or a weak/erratic output
- Damaged, frayed, or corroded wiring between the CKP and the PCM
- Loose, dirty, or damaged connector at the CKP sensor or PCM
- Oil leakage or contamination near the sensor, affecting sensing capability
- Bad ground or 5-volt reference wiring to the CKP circuit
- Worn or damaged reluctor/trigger ring or timing components
- PCM/ECU fault or software/firmware issue affecting signal interpretation
Electrical or mechanical problems in any of these areas can produce unstable CKP signals, leading to a P0335 code. Some vehicles also present related codes such as P0336 (CRC/Performance issues) interdependently.
How to diagnose P0335 (step-by-step)
Use a structured approach to verify the circuit integrity and identify the faulty component. The following steps are commonly used by technicians.
- Confirm the code with a reliable scan tool and review freeze-frame data to understand the engine state when the fault occurred.
- Visually inspect the CKP sensor and wiring harness for damage, oil leakage, abrasion, or corrosion; check connectors for security and cleanliness.
- Check battery voltage and charging system; ensure there are no voltage dips that could affect sensor readings.
- Verify the CKP 5-volt reference and ground circuits with a multimeter or professional test tool; look for continuity and proper resistance values as specified in the service manual.
- Monitor live data for CKP signal and engine RPM to see if the sensor provides a clean, irregular or missing signal; use an oscilloscope if available for precise waveform analysis.
- Inspect the reluctor ring or timing wheel for damage, misalignment, or debris that could disturb the sensor’s reading.
- If wiring and sensor checks pass but the problem persists, consider testing the PCM input or performing a software update/flash as recommended by the manufacturer.
- Based on findings, replace the faulty component (sensor, harness, or related hardware) and re-test to confirm the problem is resolved.
Accurate diagnosis often requires comparing readings to the vehicle’s service manual or a repair database. If you do not have access to an oscilloscope or vehicle-specific schematics, professional diagnostic help is recommended.
Repair options for P0335
Once the root cause is identified, the repair typically falls into one of these categories. Start with the least invasive solution and progress as needed.
- Replace the CKP sensor with an OEM or high-quality aftermarket unit designed for your engine; ensure correct variant (some engines have multiple CKP sensors).
- Repair or replace the wiring harness and connector to restore clean signal paths; fix damaged insulation, corrosion, or loose pins; apply dielectric grease as recommended.
- Clean or replace the CKP sensor’s mounting area and check for oil leaks that could contaminate the sensor; fix leaks to keep the sensor dry.
- Repair damaged or worn reluctor ring or timing components if misalignment or physical damage is found; re-torque or replace as specified.
- Address ground and 5V reference faults by repairing or replacing faulty wiring, fuses, or connections; ensure solid electrical grounding.
- If the PCM is suspected, perform the manufacturer-recommended software update or reflash; in rare cases, PCM replacement may be required.
After performing repairs, clear the codes and test drive the vehicle to confirm the problem is resolved and that no new codes reappear.
Safety considerations and when to seek help
Electrical diagnostics involve wiring and live circuits. If you are unsure or uncomfortable with high-voltage systems, or if your vehicle’s wiring runs near airbags or other sensitive systems, seek professional assistance. Always disconnect the battery before working on electrical connections and follow the vehicle’s service manual for proper procedures.
Summary
P0335 signals a fault in the crankshaft position sensor circuit A, which can lead to no-start conditions, stalling, or rough running. Diagnosis centers on verifying the sensor, its wiring, and the reference/ground circuits, plus inspecting the reluctor ring and timing components. Fixes typically include replacing the CKP sensor, repairing wiring or connectors, correcting oil contamination, and sometimes updating the PCM software. A methodical, data-driven approach—using a reliable scan tool, live data, and manual checks—yields the most reliable resolution. If in doubt, consult a qualified technician.