How To Fix A P0335 Code

So, your check engine light is on, and your OBDII scanner is showing a P0335 code. That stands for Crankshaft Position Sensor A Circuit Malfunction. Don't panic! While it sounds serious, it's a fairly common issue, and often, with a little know-how, it can be resolved without breaking the bank. Ignoring it, however, can lead to much bigger problems. This article will walk you through the symptoms, causes, what happens if you ignore it, and the recommended fixes to get you back on the road.

Symptoms of a P0335 Code

The P0335 code is a signal that something is amiss with the crankshaft position sensor or its circuit. This sensor plays a critical role in your engine's operation, so the symptoms can be quite noticeable. Here's what you might experience:

Check Engine Light: This is the most obvious sign. The P0335 code will trigger the Malfunction Indicator Lamp (MIL), also known as the check engine light.
Engine Stalling: One of the most common and concerning symptoms. The engine may stall intermittently, especially at idle or when decelerating.
Difficulty Starting: You might find it hard to start the engine. It may crank for an extended period, or not start at all.
Engine Misfires: The engine might run rough, with noticeable misfires. This is because the engine control unit (ECU) relies on the crankshaft position sensor to time the ignition and fuel injection accurately.
Decreased Fuel Economy: Poor engine performance due to misfires and timing issues can lead to a noticeable drop in fuel economy.
Hesitation or Lack of Power: You may experience hesitation during acceleration or a general lack of power.
No Start Condition: In severe cases, the engine may not start at all. This happens when the ECU cannot determine the crankshaft position and therefore cannot initiate the ignition or fuel injection sequences.
Rough Idling: The engine may idle roughly or erratically.

Understanding the Root Cause

The crankshaft position sensor (CKP sensor) is a vital component that monitors the position and rotational speed of the crankshaft. This information is then relayed to the engine control unit (ECU), which uses it to manage ignition timing, fuel injection, and other critical engine functions. A malfunction in the CKP sensor or its circuit can disrupt these processes, leading to the P0335 code.

Here are the common root causes:

Faulty Crankshaft Position Sensor: The sensor itself may be damaged or failing due to age, heat, or physical impact. This is the most frequent cause.
Wiring Issues: Damaged, corroded, or loose wiring connected to the CKP sensor can interrupt the signal flow. This includes shorts to ground or open circuits.
Connector Problems: The connector that plugs into the CKP sensor can become corroded, loose, or damaged, preventing a proper connection.
Timing Belt/Chain Issues: If the timing belt or chain is stretched, worn, or has jumped a tooth, it can affect the crankshaft's position relative to the camshaft, leading to inaccurate readings. While this often throws other codes alongside P0335, it's important to consider, especially on higher mileage vehicles.
ECU Malfunction: In rare cases, the ECU itself may be faulty and misinterpreting the signal from the CKP sensor.
Reluctor Ring Damage: The reluctor ring (also called a tone wheel or trigger wheel) is a toothed wheel attached to the crankshaft that the CKP sensor reads. If this ring is damaged or bent, it can produce an inaccurate signal.
Excessive Metallic Debris: Metallic debris accumulating around the sensor can interfere with its operation.

What Happens If You Ignore the P0335 Code?

Ignoring a P0335 code is never a good idea. While your car might seem to be running okay initially, the underlying problem will likely worsen over time, leading to more serious and costly issues. Here's what can happen:

Complete Engine Failure: Continued misfires and stalling can put undue stress on the engine components, potentially leading to catastrophic engine failure.
Catalytic Converter Damage: Misfires can send unburnt fuel into the exhaust system, damaging the catalytic converter, a very expensive repair.
Increased Fuel Consumption: As the engine struggles to operate efficiently, your fuel economy will continue to decline.
Inability to Drive: Eventually, the engine may become completely undrivable, leaving you stranded.
Safety Hazard: Stalling at inopportune moments, such as in traffic, can create a dangerous situation for you and other drivers.

Recommended Fixes

Here's a step-by-step approach to diagnosing and fixing a P0335 code:

Visual Inspection: Start by visually inspecting the CKP sensor, its wiring, and connector. Look for any signs of damage, corrosion, or loose connections. Clean any corrosion you find and ensure the connector is securely attached.
Check the Wiring: Use a multimeter to check the continuity and voltage of the CKP sensor wiring. Refer to your vehicle's repair manual for the correct specifications. Look for any shorts to ground or open circuits. Repair or replace any damaged wiring.
Inspect the Reluctor Ring: If possible, visually inspect the reluctor ring for damage or misalignment. This may require removing the CKP sensor or other components.
Test the CKP Sensor: Use a multimeter or oscilloscope to test the CKP sensor's output signal. Compare the readings to the specifications in your vehicle's repair manual. If the sensor is not producing a proper signal, it likely needs to be replaced.
Replace the CKP Sensor: If the sensor is faulty, replace it with a new, high-quality sensor. Make sure to use the correct sensor for your vehicle.
Check the Timing Belt/Chain: Inspect the timing belt or chain for wear, stretching, or damage. If necessary, replace it according to the manufacturer's recommendations. This is especially important if your vehicle has high mileage.
Clear the Code and Retest: After making any repairs, clear the P0335 code using an OBDII scanner. Then, start the engine and monitor it to see if the code returns.
Consult a Professional: If you're not comfortable performing these repairs yourself, or if the problem persists after trying these steps, it's best to consult a qualified mechanic. They have the tools and expertise to diagnose and repair complex engine issues.

Cost Estimates and Shop Advice

The cost to fix a P0335 code can vary depending on the root cause and the extent of the repairs needed. Here's a general breakdown:

Crankshaft Position Sensor Replacement: This is the most common repair. The cost of the sensor itself can range from $30 to $150, depending on the make and model of your vehicle. Labor costs can vary, but typically range from $50 to $150, depending on the sensor's location and accessibility. Total cost: $80 - $300.
Wiring Repair: If the problem is with the wiring, the cost will depend on the extent of the damage and the labor required to repair or replace the wiring harness. This can range from $50 to $300.
Timing Belt/Chain Replacement: This is a more extensive repair and can be quite costly. The cost of the timing belt/chain kit can range from $100 to $500, and labor costs can range from $300 to $1000 or more, depending on the vehicle. Total cost: $400 - $1500.
ECU Replacement: This is the least common repair and the most expensive. The cost of a new ECU can range from $500 to $2000, and labor costs can range from $100 to $300.

Shop Advice:

Get a Diagnostic Scan: Before authorizing any repairs, ask the mechanic to perform a thorough diagnostic scan to confirm the P0335 code and identify the root cause.
Ask for a Detailed Estimate: Get a written estimate that includes the cost of parts, labor, and any other associated fees.
Inquire About Warranty: Ask about the warranty on the parts and labor.
Read Reviews: Before choosing a mechanic, check online reviews to see what other customers have to say about their experience.
Consider a Second Opinion: If you're unsure about the diagnosis or estimate, consider getting a second opinion from another mechanic.

Credibility and Additional Information

It's worth noting that some manufacturers have issued Technical Service Bulletins (TSBs) related to the P0335 code. These TSBs provide specific diagnostic and repair procedures for certain vehicle models. For example, some older Honda models (late 90s-early 2000s) have documented issues with the CKP sensor wiring harness degrading due to heat and vibration, leading to intermittent P0335 codes. Always check for relevant TSBs for your specific vehicle make and model. You can usually find these on the National Highway Traffic Safety Administration (NHTSA) website or through a reputable online repair database.

Additionally, online forums and communities dedicated to specific vehicle makes and models can provide valuable insights into common issues and solutions. Many owners have shared their experiences with the P0335 code, including common mileage at which the sensor fails. This information can help you anticipate potential problems and take preventative measures.

While the P0335 code can be concerning, understanding the symptoms, causes, and recommended fixes can empower you to take the necessary steps to resolve the issue and keep your vehicle running smoothly. Remember to prioritize safety, perform thorough diagnostics, and consult a qualified mechanic when needed.