OBD-II Code P0335: Crankshaft Position Sensor “A” Circuit Malfunction – Diagnosis and Repair Guide

Navigating car troubles can be stressful, especially when the check engine light illuminates. Among the numerous diagnostic trouble codes (DTCs) your vehicle might display, P0335 is a common one related to engine performance. As a content creator for autelfrance.com and an auto repair expert, I’m here to break down this code, explain its implications, and guide you through potential solutions.

The OBD-II code P0335, specifically “Crankshaft Position Sensor A Circuit Malfunction,” indicates an issue within the circuit of the Crankshaft Position Sensor (CKP). This sensor is crucial for your engine’s operation, acting as a vital communication link between the mechanical rotation of the crankshaft and your car’s computer, the Powertrain Control Module (PCM).

Understanding the Crankshaft Position Sensor (CKP) and Code P0335

The Crankshaft Position Sensor’s primary role is to monitor the crankshaft’s position and rotational speed. It achieves this by working in tandem with a reluctor ring, also known as a tone wheel or toothed ring, attached to the crankshaft. As the crankshaft rotates, the reluctor ring passes by the CKP sensor. This interaction disrupts the magnetic field of the sensor, generating a voltage signal. This signal is then transmitted to the PCM as a series of pulses, which the computer interprets to determine the crankshaft’s exact position and speed.

Alt text: Diagram illustrating a crankshaft position sensor and reluctor ring, highlighting their interaction in generating engine speed and position signals.

The PCM relies on this information for several critical functions, which vary slightly depending on your vehicle’s make and model:

• Ignition Timing: In many vehicles, the PCM uses CKP data to precisely time the spark plugs’ firing, ensuring optimal combustion and engine performance.
• Fuel Injection Timing: Similar to ignition, accurate crankshaft position data is essential for the PCM to time fuel injection events correctly, maximizing fuel efficiency and power.
• Misfire Detection: Even in systems where the CKP doesn’t directly control spark timing, it’s crucial for detecting engine misfires. By monitoring crankshaft speed fluctuations, the PCM can identify irregularities indicative of a cylinder misfiring.

When the PCM detects an anomaly in the CKP sensor circuit – such as a missing signal, an erratic signal, or a complete lack of signal – it triggers the P0335 code. This indicates a potential malfunction that needs immediate attention.

Symptoms Associated with OBD-II Code P0335

The severity of symptoms associated with P0335 can vary depending on whether the CKP sensor is solely used for misfire detection or also controls ignition and fuel timing.

• Engine Won’t Start: If the CKP sensor is critical for spark and fuel timing, a P0335 code can prevent your engine from starting altogether. The PCM won’t initiate these functions without reliable crankshaft position data.
• Rough Running or Misfiring Engine: If the engine does start, it may run erratically, exhibiting rough idling, hesitation, and misfires. This occurs because the PCM is operating with inaccurate or incomplete crankshaft information, leading to mistimed combustion events.
• Check Engine Light (MIL) Illumination: The most immediate and obvious symptom is the illumination of your Malfunction Indicator Lamp (MIL), commonly known as the check engine light. This light signals that the PCM has detected a problem and stored the P0335 code.
• Stalling: In some cases, especially with intermittent CKP sensor issues, the engine might stall unexpectedly while driving.
• Lack of Power: Due to mistimed combustion and potential misfires, you might experience a noticeable decrease in engine power and acceleration.

It’s important to note that in some vehicles where the CKP sensor is primarily for misfire detection, the vehicle might still start and run with the P0335 code present, albeit with the check engine light on. However, prolonged driving with this issue is not recommended as it can lead to further engine problems and reduced fuel efficiency.

Potential Causes of a P0335 Code

Pinpointing the exact cause of a P0335 code requires systematic diagnosis. Here are the common culprits:

• Faulty Crankshaft Position Sensor: The sensor itself might be failing due to age, wear and tear, or internal damage. This is often the most frequent cause.
• CKP Sensor Wiring or Connector Issues: Damage to the wiring harness leading to the CKP sensor, or a loose or corroded connector, can disrupt the signal. This includes:
  • Open Circuit: A break in the wiring preventing signal flow.
  • Short Circuit to Ground: The sensor signal wire is shorting to ground, disrupting the voltage signal.
  • Short Circuit to Voltage: The sensor signal wire is shorting to a voltage source, causing an incorrect signal.

Alt text: Image showcasing a technician inspecting a crankshaft position sensor connector and wiring for signs of damage or corrosion, common causes of P0335 errors.

• Reluctor Ring Damage: If the reluctor ring is damaged, bent, or has missing teeth, it will not generate the correct signal as it passes the CKP sensor. Damage can occur due to debris, impact, or in rare cases, manufacturing defects.
• Timing Belt/Chain Issues: A broken or severely stretched timing belt or chain can disrupt the synchronization between the crankshaft and camshaft, potentially affecting the CKP sensor signal indirectly or causing broader engine timing problems that trigger P0335.
• Powertrain Control Module (PCM) Failure: While less common, a faulty PCM could misinterpret the CKP sensor signal or incorrectly diagnose a circuit malfunction. This is usually considered after ruling out other potential causes.

Diagnosing and Resolving OBD-II Code P0335

Diagnosing P0335 requires a methodical approach. Here’s a step-by-step troubleshooting process:

1. Initial Scan and RPM Check: Using an OBD-II scan tool, verify the presence of the P0335 code and check for any other related codes. Crucially, check if the scan tool registers an RPM signal while cranking the engine.

   • No RPM Signal: This strongly suggests a CKP sensor or circuit issue. Proceed to further inspection of the sensor and wiring.
   • RPM Signal Present (but code P0335 persists): This is less common but could indicate an intermittent fault, a wiring issue, or potentially a PCM problem.

2. Visual Inspection: Thoroughly inspect the CKP sensor, its connector, and the wiring harness for any visible signs of damage, such as:

   • Broken or cracked sensor housing
   • Loose or corroded connector pins
   • Damaged, frayed, or melted wires

   Repair or replace any damaged components as needed. Ensure the connector is securely fastened.

3. Sensor Resistance Test: Consult your vehicle’s repair manual for the correct resistance specifications for your CKP sensor. Disconnect the sensor and use a multimeter to measure its resistance. Compare the reading to the specified range.

   • Resistance Out of Specification: Replace the CKP sensor.
   • Resistance Within Specification: The sensor itself might be functioning correctly, indicating a potential wiring or PCM issue.

4. Wiring Circuit Tests: If the sensor resistance is within spec, the next step is to test the wiring circuit between the CKP sensor and the PCM. This requires a wiring diagram for your vehicle and involves checking for:

   • Continuity: Ensure there are no breaks in the wires (open circuits).
   • Shorts to Ground/Voltage: Check for shorts to ground or voltage using a multimeter.

   Repair any wiring faults identified. This step may require advanced electrical troubleshooting skills and is best performed by a qualified technician if you are not comfortable with automotive electrical systems.

5. Reluctor Ring Inspection: If accessible, visually inspect the reluctor ring for damage or debris. In some cases, this requires removing the sensor to get a clear view. Damage to the reluctor ring necessitates professional repair, potentially involving crankshaft or component replacement.

6. PCM as Last Resort: If all other components and wiring check out, and the P0335 code persists, a faulty PCM is a possibility, although less likely. PCM diagnosis and replacement should be performed by experienced technicians.

7. Clear Codes and Retest: After performing any repairs, clear the P0335 code using a scan tool and retest the system. Start the engine and monitor for the code to return. If the code is resolved, perform a test drive to ensure the issue is fully fixed.

Important Note: Diagnosing and repairing OBD-II codes can involve working with electrical and mechanical systems. If you are not comfortable or experienced with auto repair, it is always recommended to consult a certified mechanic.

Conclusion

OBD-II code P0335 signals a malfunction in the Crankshaft Position Sensor “A” circuit, a critical component for engine operation. Understanding the sensor’s function, recognizing the symptoms, and following a systematic diagnostic process are key to resolving this issue. While some repairs, like sensor or connector replacement, can be DIY-friendly, complex wiring or PCM issues often require professional expertise. By addressing P0335 promptly, you can ensure your vehicle’s engine runs smoothly and avoid potential further damage.

For further assistance and to share your experiences with P0335 or other car repair issues, don’t hesitate to visit our FREE car repair forums at autelfrance.com. Our community of experts and enthusiasts is here to help!