A bad crankshaft position sensor can trigger several diagnostic trouble codes (DTCs), with the most common being P0335 (Crankshaft Position Sensor “A” Circuit Malfunction). Other related codes include P0336, P0337, P0338, and P0339, which indicate various issues such as signal range problems, low or high input, and intermittent sensor operation. These codes typically lead to symptoms like engine misfires, stalling, and difficulty starting the engine.
The crankshaft position sensor (CKP) is a vital component in modern internal combustion engines, responsible for monitoring the position and rotational speed of the crankshaft. This information is crucial for engine management systems, particularly for controlling ignition timing and fuel injection. When the crankshaft sensor malfunctions, it can trigger various diagnostic trouble codes (DTCs) that are essential for identifying the issue.
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Symptoms of a Bad Crankshaft Position Sensor
When the crankshaft sensor starts to fail, your vehicle may exhibit several symptoms, including:
- Engine Misfires: A faulty crankshaft sensor can cause misfires, as the ECM may not receive accurate timing signals.
- Difficulty Starting the Engine: Since the sensor helps determine when to fire the spark plugs, a bad sensor can make starting the engine difficult or impossible.
- Stalling: The engine may stall unexpectedly if the crankshaft sensor fails while the vehicle is running.
- Reduced Engine Performance: A malfunctioning sensor can cause poor acceleration and reduced fuel efficiency.
These symptoms can be frustrating and, if ignored, can lead to more severe engine damage. Therefore, understanding the trouble codes associated with a faulty crankshaft sensor is crucial for timely diagnosis and repair.
Trouble Codes (DTCs) Caused by a Bad Crankshaft Sensor
When the crankshaft sensor malfunctions, the ECM or PCM will usually generate a specific set of trouble codes. Here are the most common DTCs associated with a bad crankshaft sensor:
- P0335: Crankshaft Position Sensor “A” Circuit Malfunction
- Description: This code indicates a malfunction in the electrical circuit of the crankshaft position sensor “A.” It could be due to a faulty sensor, wiring issues, or a problem with the ECM.
- Symptoms: Engine stalling, difficulty starting, and engine misfires.
- Possible Causes: Damaged wiring or connectors, a faulty crankshaft sensor, or a defective ECM.
- Repair: Inspect the wiring and connectors for damage, and replace the crankshaft sensor if necessary.
- P0336: Crankshaft Position Sensor “A” Circuit Range/Performance
- Description: This code is triggered when the signal from the crankshaft sensor is out of the expected range or is not performing as it should.
- Symptoms: Similar to P0335, including poor engine performance and stalling.
- Possible Causes: Worn or damaged crankshaft sensor, incorrect sensor installation, or issues with the reluctor ring on the crankshaft.
- Repair: Check the sensor installation, inspect the reluctor ring, and replace the sensor if needed.
- P0337: Crankshaft Position Sensor “A” Circuit Low Input
- Description: This code indicates that the signal from the crankshaft sensor is too low, suggesting a weak or faulty sensor.
- Symptoms: Engine stalling, no start condition, and intermittent misfires.
- Possible Causes: Faulty sensor, damaged wiring, or ECM issues.
- Repair: Test the sensor’s output voltage and inspect the wiring for any damage.
- P0338: Crankshaft Position Sensor “A” Circuit High Input
- Description: This code is triggered when the crankshaft sensor produces a signal that is higher than expected, indicating a potential short circuit or a failing sensor.
- Symptoms: Engine hesitation, poor fuel economy, and possible engine misfires.
- Possible Causes: Short circuits, faulty sensor, or ECM problems.
- Repair: Inspect the wiring for shorts, test the sensor, and replace it if necessary.
- P0339: Crankshaft Position Sensor “A” Circuit Intermittent
- Description: This code indicates that the signal from the crankshaft sensor is intermittent, meaning it may be cutting in and out.
- Symptoms: Erratic engine performance, stalling, and difficulty starting the engine.
- Possible Causes: Loose or corroded wiring, failing sensor, or problems with the ECM.
- Repair: Inspect and secure the wiring connections, and replace the sensor if the issue persists.
- P0340: Camshaft Position Sensor Circuit Malfunction
- Description: Although this code primarily pertains to the camshaft position sensor, it can also be triggered by issues with the crankshaft sensor, as both sensors work in tandem.
- Symptoms: Engine misfires, stalling, and difficulty starting.
- Possible Causes: Faulty camshaft or crankshaft sensor, wiring issues, or ECM problems.
- Repair: Inspect both the camshaft and crankshaft sensors, check the wiring, and replace faulty components.
How to Fix Crankshaft Sensor Issues
When one of the above codes appears, it’s crucial to perform a thorough diagnosis to pinpoint the exact cause of the problem. Here’s a step-by-step guide to diagnosing a bad crankshaft sensor:
- Scan for Codes: Use an OBD-II scanner to retrieve the trouble codes stored in the ECM. This will give you a starting point for your diagnosis.
- Visual Inspection: Check the wiring and connectors associated with the crankshaft sensor for any signs of damage, corrosion, or disconnection.
- Test the Sensor: Depending on the type of sensor (inductive or Hall-effect), use a multimeter to test the sensor’s resistance, output voltage, or signal waveform. Compare the results with the manufacturer’s specifications.
- Check the Reluctor Ring: Inspect the reluctor ring on the crankshaft for any signs of damage, such as missing teeth or cracks. A damaged reluctor ring can cause inaccurate signals from the sensor.
- Replace the Sensor: If the sensor is found to be faulty, replace it with a new one. Make sure the replacement sensor is compatible with your vehicle’s make and model.
- Clear the Codes: After replacing the sensor, clear the trouble codes from the ECM using the OBD-II scanner. Start the engine and check if the codes reappear.
- Road Test: Finally, take the vehicle for a road test to ensure that the issue has been resolved and that the engine runs smoothly.
Frequently Asked Questions
Here are some FAQs about the bad crankshaft sensor code –
1. What happens if I ignore a faulty crankshaft sensor?
Ignoring a faulty crankshaft sensor can lead to severe engine problems, including misfires, stalling, and even engine failure. It’s crucial to address the issue promptly to avoid costly repairs.
2. Can a crankshaft sensor be cleaned instead of replaced?
In some cases, cleaning the sensor might resolve the issue, especially if it’s contaminated with dirt or oil. However, if the sensor is damaged or worn out, replacement is the only solution.
3. How much does it cost to replace a crankshaft sensor?
The cost of replacing a crankshaft sensor varies depending on the make and model of your vehicle. On average, the cost ranges from $120 to $300, including parts and labor.
4. Can I drive my car with a bad crankshaft sensor?
While it might be possible to drive with a bad crankshaft sensor, it’s not recommended. A malfunctioning sensor can lead to poor engine performance, stalling, and increased risk of engine damage.
5. How long does a crankshaft sensor typically last?
A crankshaft sensor can last for several years, depending on the vehicle and driving conditions. However, like any component, it can wear out over time and may need replacement after 100,000 to 150,000 miles.
Conclusion
The crankshaft position sensor is a critical component in ensuring your engine runs smoothly. A malfunctioning sensor can cause a range of trouble codes, each indicating a specific issue that needs to be addressed. By understanding these codes and their associated symptoms, you can take the necessary steps to diagnose and repair the problem, ensuring your vehicle remains in optimal condition.