OBD2 Code P0335: Crankshaft Position Sensor A Circuit Malfunction Explained

The OBD2 code P0335 indicates a “Crankshaft Position Sensor A Circuit Malfunction”. This is a generic powertrain code, meaning it applies to vehicles equipped with OBD-II systems across various makes and models. While the definition is universal, specific repair steps can differ depending on the vehicle manufacturer and model.

This article, brought to you by the experts at techcarusa.com, will delve into the intricacies of the P0335 code, providing a comprehensive understanding of its meaning, symptoms, causes, and effective diagnostic and repair strategies. We aim to equip you with the knowledge to tackle this issue effectively, whether you are a seasoned mechanic or a car owner keen on understanding your vehicle better.

Understanding the P0335 Code: Crankshaft Position Sensor A Circuit Malfunction

To grasp the P0335 code, it’s crucial to understand the role of the Crankshaft Position Sensor (CKP) in your vehicle’s engine management system.

What Does the Crankshaft Position Sensor Do?

The Crankshaft Position Sensor (CKP) is a vital component that monitors the position and rotational speed of the crankshaft. This information is relayed to the Powertrain Control Module (PCM), the brain of your car’s engine management system. The PCM utilizes this data for several critical functions, including:

• Ignition Timing: In many vehicles, the PCM uses CKP sensor data to precisely time the ignition spark, ensuring optimal combustion and engine performance.
• Fuel Injection Timing: Similarly, the CKP sensor helps the PCM time fuel injection events, optimizing fuel delivery for efficiency and power.
• Misfire Detection: Even in systems where the CKP sensor doesn’t control spark timing, it plays a crucial role in detecting engine misfires. By monitoring crankshaft speed fluctuations, the PCM can identify if a cylinder is not firing correctly.

The CKP sensor operates in conjunction with a reluctor ring, also known as a toothed ring, attached to the crankshaft. As the crankshaft rotates, the reluctor ring passes by the CKP sensor. This interaction disrupts the magnetic field generated by the CKP sensor, creating a square wave voltage signal. The PCM interprets these pulses as crankshaft position and speed.

This image depicts a typical crankshaft position sensor. The sensor is strategically positioned to read the reluctor ring on the crankshaft, providing crucial data for engine management.

When the PCM detects an absence of these crankshaft pulses or identifies irregularities in the output circuit signal from the CKP sensor “A”, it triggers the P0335 trouble code. The designation “A” often refers to a specific sensor in systems with multiple CKP sensors, although in many vehicles, there is only one.

Decoding “Circuit Malfunction”

The “Circuit Malfunction” part of the P0335 code is significant. It indicates that the PCM has detected an electrical issue within the CKP sensor circuit. This could encompass a range of problems, from wiring faults to internal sensor failures, impacting the sensor’s ability to transmit accurate data.

Symptoms of a P0335 Code

The symptoms of a P0335 code can vary depending on whether the CKP sensor is solely used for misfire detection or also controls spark timing. In vehicles where the CKP sensor is only for misfire detection, the symptoms might be less immediately noticeable, but the underlying issue can still affect performance and potentially lead to more severe problems.

Here are common symptoms associated with the P0335 code:

• Check Engine Light (MIL Illumination): This is often the first and most obvious sign. The Malfunction Indicator Lamp (MIL), or check engine light, will illuminate on your dashboard to alert you to a detected issue. Note that some vehicles may require multiple drive cycles for the MIL to illuminate.
• Vehicle May Not Start: If the CKP sensor is critical for spark timing, a P0335 code can prevent the engine from starting altogether. The PCM relies on the CKP signal to initiate ignition and fuel delivery, and a faulty signal can disrupt this process.
• Rough Running or Engine Misfires: Even if the vehicle starts, a malfunctioning CKP sensor can lead to erratic engine performance. This can manifest as rough idling, hesitation during acceleration, and noticeable engine misfires. These symptoms arise from the PCM’s inability to accurately time ignition and fuel injection due to faulty CKP sensor data.
• Engine Stalling: In some cases, a P0335 code can cause the engine to stall unexpectedly. This is more likely to occur if the CKP sensor signal becomes intermittent or completely drops out while driving.
• Reduced Engine Performance: Even without stalling or severe misfires, a P0335 code can lead to a general decrease in engine power and responsiveness. The inaccurate timing and fuel delivery can compromise combustion efficiency, resulting in sluggish performance.

It’s crucial to address a P0335 code promptly. Ignoring these symptoms can lead to further engine damage and potentially more costly repairs down the line.

Potential Causes of OBD2 Code P0335

The P0335 code, signaling a Crankshaft Position Sensor A Circuit Malfunction, can stem from a variety of underlying issues within the CKP sensor system. Identifying the precise cause is essential for effective repair. Here are the common culprits behind a P0335 code:

• Damaged CKP Sensor Connector: The electrical connector for the CKP sensor is exposed to engine bay conditions and vibrations. It can become corroded, loose, or physically damaged, leading to poor electrical contact and signal disruption.
• Damaged Reluctor Ring: The reluctor ring, or toothed ring, is crucial for the CKP sensor’s operation. If this ring is damaged – for example, with missing teeth, cracks, or misalignment – it will disrupt the magnetic field and generate an inaccurate signal, or no signal at all. Damage to the reluctor ring can sometimes occur due to debris or during engine work. In some severe cases, a sheared-off keyway preventing the reluctor ring from turning with the crankshaft can also trigger this code.
• CKP Sensor Wiring Issues: The wiring harness connecting the CKP sensor to the PCM is susceptible to damage. This can include:
  • Open Circuit: A break in the wire, preventing the signal from reaching the PCM.
  • Short to Ground: The sensor signal wire may be shorting to the vehicle’s chassis ground, disrupting the signal.
  • Short to Voltage: The sensor signal wire may be shorting to a voltage source, feeding incorrect voltage back to the PCM.
    Wiring damage can be caused by heat, vibration, abrasion, or rodent activity.
• Failed CKP Sensor: The CKP sensor itself can fail internally. Like any electronic component, it has a lifespan and can degrade over time due to heat, vibration, and general wear and tear. A faulty sensor may not generate a signal or may produce an erratic or inaccurate signal.
• Broken Timing Belt or Timing Chain Issues: Although less common, a severely worn or broken timing belt or a stretched timing chain can affect the relationship between the crankshaft and camshaft. This can lead to timing discrepancies that might trigger a P0335 code, especially if the PCM relies on both crankshaft and camshaft sensor data for timing calculations. However, timing belt/chain issues usually trigger other codes in conjunction with P0335.
• Failed PCM (Powertrain Control Module): In rare cases, the PCM itself may be faulty. While less frequent than sensor or wiring issues, a malfunctioning PCM can misinterpret sensor signals or incorrectly diagnose a CKP sensor circuit problem. PCM failure is usually considered as a last resort diagnosis after ruling out all other possibilities.

This image illustrates a common location for a crankshaft position sensor on an engine block. Its proximity to the crankshaft and reluctor ring is evident.

Diagnosing and Fixing P0335: Step-by-Step Guide

Diagnosing a P0335 code requires a systematic approach to pinpoint the root cause. Here’s a step-by-step guide you can follow:

1. Initial Scan and RPM Check: Use an OBD-II scan tool to confirm the presence of the P0335 code and check for any other related trouble codes. Crucially, while the engine is cranking or running (if possible), observe the scan tool’s data stream for an RPM signal.

   • No RPM Signal: If there is no RPM reading while cranking, this strongly suggests an issue with the CKP sensor, its circuit, or the reluctor ring. Proceed to step 2.
   • RPM Signal Present: If an RPM signal is present, the issue might be intermittent, or the code could be triggered by a temporary glitch. Clear the code and see if it returns. If it does, further investigation is needed, but the CKP sensor itself is less likely to be completely faulty.

2. Visual Inspection of CKP Sensor and Connector: Carefully inspect the CKP sensor and its connector for any obvious signs of damage. Look for:

   • Connector Damage: Check for broken, bent, or corroded connector pins. Ensure the connector is securely attached to the sensor.
   • Sensor Damage: Examine the sensor for physical damage, cracks, or oil contamination.
   • Wiring Damage (Visible): Inspect the wiring harness near the sensor for any frayed, cut, or melted wires.

   Repair any visible damage to the connector or wiring. If the connector is severely damaged, consider replacing it.

3. Reluctor Ring Inspection (If Accessible): If possible, visually inspect the reluctor ring for damage. This may require removing the CKP sensor and possibly using a mirror or inspection camera to get a good view. Look for:

   • Missing Teeth: Check if any teeth on the reluctor ring are broken or missing.
   • Damage or Debris: Ensure the reluctor ring is clean and free of debris that could interfere with the sensor’s signal.
   • Secure Mounting: Verify the reluctor ring is securely mounted to the crankshaft and rotates true.

4. CKP Sensor Resistance Test: Obtain the specified resistance range for your vehicle’s CKP sensor from a repair manual or reliable online resource. Disconnect the CKP sensor and use a multimeter to measure the sensor’s resistance.

   • Out of Specification: If the resistance reading is outside the specified range, the CKP sensor is likely faulty and needs replacement.
   • Within Specification: If the resistance is within spec, the sensor itself might be okay, and the problem could lie in the wiring or PCM.

5. Wiring Circuit Tests: Perform circuit tests on the CKP sensor wiring harness to check for open circuits, shorts to ground, and shorts to voltage. You will need a wiring diagram for your specific vehicle.

   • Continuity Test: Check for continuity in each wire of the CKP sensor circuit to rule out open circuits.
   • Short to Ground Test: Check for shorts to ground by testing for continuity between each wire and a known good ground point.
   • Short to Voltage Test: Check for shorts to voltage by testing for voltage on each wire with the ignition on (and sensor disconnected).

   Repair any wiring issues (opens, shorts) as needed.

6. PCM Connector Resistance Check (Advanced): For a more comprehensive check, and if you are comfortable working with automotive electrical systems, you can check the CKP sensor circuit resistance from the PCM connector. This will rule out wiring problems from the sensor all the way to the PCM. Compare the reading to the sensor resistance reading taken directly at the sensor. Significant differences indicate wiring issues. Caution: This step requires caution and should only be performed by individuals familiar with automotive electrical systems.

7. Sensor Replacement: If the CKP sensor resistance is out of specification, or if all wiring and reluctor ring issues have been ruled out, replace the CKP sensor with a new, quality replacement part. After replacement, clear the P0335 code and re-scan to see if it returns.

8. PCM as Last Resort: If all other diagnostic steps have been exhausted and the P0335 code persists, a faulty PCM might be the cause. However, PCM replacement should be considered as a last resort and often requires professional diagnosis and programming.

Important Note: Always consult your vehicle’s repair manual for specific diagnostic procedures and component locations. If you are not comfortable performing these diagnostic steps, it’s best to seek assistance from a qualified mechanic.

Related OBD-II Codes

The P0335 code is closely related to other crankshaft and camshaft position sensor codes. Understanding these related codes can sometimes provide additional context during diagnosis. The most directly related code is P0385, which refers to “Crankshaft Position Sensor B Circuit Malfunction”. This code is essentially identical to P0335 but indicates an issue with a secondary CKP sensor in systems that utilize two sensors.

Other related codes involving crankshaft and camshaft position sensors include:

• P0016, P0017, P0018, P0019: These codes relate to camshaft and crankshaft position correlation issues, indicating potential timing problems.
• P0336, P0337, P0338, P0339: These are also CKP sensor circuit codes, indicating issues such as range/performance problems, low/high input, and intermittent circuit problems.
• P0386, P0387, P0388, P0389: These are related to Crankshaft Position Sensor “B” circuit issues, mirroring the P0336-P0339 series for sensor “A”.

Need More Help with a P0335 Code?

While this guide provides a comprehensive overview of the P0335 code, diagnosing and repairing car issues can sometimes be complex. If you find yourself needing further assistance or want to discuss your specific situation with experienced mechanics and car enthusiasts, we encourage you to visit our FREE car repair forums. There, you can post questions, share your experiences, and receive valuable advice from our community. Don’t hesitate to leverage the collective knowledge available to help you resolve your P0335 code and get your vehicle running smoothly again.