P0335 — Crankshaft Position Sensor 'A' Circuit

Quick answer

• The P0335 code indicates a problem with the crankshaft position sensor circuit, which is crucial for engine timing.
• This is a moderately severe code; it's generally safe to drive home or to a repair shop, but prolonged driving can lead to engine issues or stalling.
• The most common cause is a faulty crankshaft position sensor.

What the P0335 code means

The P0335 code stands for "Crankshaft Position Sensor 'A' Circuit Malfunction." In simpler terms, your car's computer (the Powertrain Control Module or PCM) has detected an issue with the electrical circuit of the crankshaft position sensor. This sensor is incredibly important because it monitors the rotational speed and position of the crankshaft, sending vital information back to the PCM. The PCM uses this data to precisely control ignition timing and fuel injection, ensuring the engine runs smoothly and efficiently. When the PCM doesn't receive the expected signal from this circuit, it triggers the P0335 code.

Common symptoms

• Check Engine Light illumination: This is almost always the first sign.
• Engine cranking but no start: If the PCM can't determine crankshaft position, it won't know when to fire the spark plugs or inject fuel.
• Intermittent stalling: The engine may suddenly shut off while driving.
• Rough idle or misfires: Incorrect timing due to faulty sensor data can cause the engine to run poorly.
• Hesitation or poor acceleration: The engine may not respond properly to throttle input.
• Reduced fuel economy: Inaccurate timing can lead to inefficient fuel combustion.
• Engine surging: The engine RPMs may fluctuate unexpectedly.

Common causes

1. Faulty Crankshaft Position Sensor: This is by far the most common culprit. Sensors can fail internally due to age, heat, or vibration.
2. Wiring harness issues: Damaged, corroded, or shorted wires or connectors in the crankshaft position sensor circuit can disrupt the signal. This can be caused by rodents, heat, or wear.
3. Loose or corroded electrical connections: A poor connection at the sensor or PCM can lead to intermittent or absent signals.
4. Damaged reluctor wheel (tone ring): The crankshaft position sensor reads teeth on a reluctor wheel mounted on the crankshaft. If this wheel is damaged, bent, or has missing teeth, the sensor won't get an accurate reading.
5. PCM failure: While rare, a faulty Powertrain Control Module could incorrectly interpret the sensor's signal or fail to process it. This is usually a last resort diagnosis after ruling out all other possibilities.

How a technician diagnoses it

1. Verify the complaint and visual inspection: The technician will confirm the Check Engine Light is on and perform a thorough visual inspection of the crankshaft position sensor, its wiring, and connectors for any obvious damage, loose connections, or corrosion.
2. Scan for codes and freeze frame data: A scan tool will be connected to retrieve the P0335 code and any other related diagnostic trouble codes. The freeze frame data will be analyzed, which captures engine parameters (like engine speed, engine load, coolant temperature) at the moment the code was set. This can provide clues about the conditions when the fault occurred.
3. Clear codes and test drive: After recording the data, codes may be cleared, and a test drive performed to see if the code returns. This helps differentiate between a hard fault and an intermittent issue.
4. Crankshaft Position Sensor Resistance/Voltage Check: Using a multimeter, the technician will check the resistance of the sensor (if applicable) and/or the voltage output. Specifications vary by vehicle, but a common test involves checking for a steady AC voltage signal when the engine is cranking or running. A good sensor will typically produce a clean waveform when viewed on an oscilloscope.
5. Wiring Harness Continuity Check: The technician will use a multimeter to check for continuity, shorts, or open circuits in the wiring harness between the crankshaft position sensor and the PCM. This ensures the wiring itself is intact and not causing the signal disruption.
6. Reluctor Wheel Inspection: If the sensor and wiring check out, the technician might need to inspect the crankshaft reluctor wheel for damage or debris. This often requires removing the sensor.
7. PCM Diagnosis: Only after all other possibilities have been meticulously ruled out will the PCM be considered a potential cause. Further diagnostic steps specific to PCM testing would then be followed.

Typical repair cost

The cost to repair a P0335 code can vary depending on the exact cause and your vehicle's make and model. Here are some estimates:

• Crankshaft Position Sensor Replacement: Parts typically range from $50 to $200. Labor can range from $100 to $300, depending on accessibility, for a total of $150 to $500.
• Wiring Repair: This can vary significantly, from $75 to $400 or more, depending on the extent of the damage and location.
• Reluctor Wheel Replacement: This is a more involved repair, often requiring significant engine disassembly. Parts can range from $100 to $400, and labor could be anywhere from $400 to $1000+, for a total of $500 to $1400+.

Can I keep driving with this code?

While you might be able to drive with a P0335 code for a short distance (e.g., to a repair shop), it's generally not recommended to drive for an extended period. The crankshaft position sensor is a critical component for engine operation. Driving with this code can lead to:

• Sudden stalling: This can be dangerous, especially at highway speeds.
• Engine damage: If the timing is severely off, it can cause misfires and potentially damage internal engine components over time.
• Increased emissions and poor fuel economy.
• Inability to start the vehicle.

It's best to get this issue diagnosed and repaired as soon as possible to avoid further complications and ensure your safety.

Related codes

• P0336: Crankshaft Position Sensor 'A' Circuit Range/Performance
• P0337: Crankshaft Position Sensor 'A' Circuit Low Input
• P0338: Crankshaft Position Sensor 'A' Circuit High Input
• P0339: Crankshaft Position Sensor 'A' Intermittent Circuit
• P0340: Camshaft Position Sensor 'A' Circuit (Bank 1 or Single Sensor)

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