What is the code for a camshaft position sensor?

There isn’t a single universal “code” for a camshaft position sensor. Diagnostic trouble codes (DTCs) tied to CMP sensing typically appear as several P-codes—most commonly P0340 and related P0341–P0344—depending on the vehicle’s make, model, and year.

What follows is a detailed look at what these codes indicate, how they guide diagnostics, and practical steps for addressing CMP-related problems on modern engines.

What the CMP codes mean

The camshaft position sensor provides the engine control module (ECM) with critical timing information. When the ECM detects a signal that is missing, out of range, or inconsistent, it stores a DTC and may illuminate the Check Engine Light. CMP codes point to issues in the sensor circuit itself or in the timing reference signals that the sensor feeds the ECM.

Common CMP-Related DTCs

Before examining the list, keep in mind that the exact code can vary by manufacturer and engine design. The codes below are among the most frequently seen in relation to the camshaft position sensor.

• P0340 Camshaft Position Sensor Circuit Malfunction


• P0341 Camshaft Position Sensor A Circuit Range/Performance (Bank 1, Sensor A)


• P0342 Camshaft Position Sensor A Circuit Low Input


• P0343 Camshaft Position Sensor A Circuit High Input


• P0344 Camshaft Position Sensor A Circuit Intermittent

Note that some vehicles may label banks or sensor references differently, and manufacturers may issue additional CMP-related codes. A technician using the vehicle’s service manual and a capable scan tool can confirm the exact meaning for a given application.

Diagnosis and Troubleshooting

Diagnostics typically follows a structured approach: starting with the DTC and live data, then inspecting wiring and connectors, testing the sensor, and checking timing components.

1. Retrieve the DTCs and freeze-frame data with a scan tool to understand the conditions under which the code was stored.


2. Inspect the camshaft position sensor’s wiring and connector for corrosion, wear, or loose connections; repair or replace as needed.


3. Test the sensor signal and power supply. Verify a stable reference voltage (often 5 volts) and a clean, pulsed output using an oscilloscope or a multimeter with suitable test modes.


4. Check the reluctor ring or timing gear and camshaft timing to ensure there is no mechanical issue or timing misalignment that could cause signal loss or jitter.


5. Inspect related sensors (e.g., crankshaft position sensor) and ECM software; some symptoms can involve multiple timing sensors or data interpretation by the ECU.


6. Clear codes after repairs and test-drive the vehicle to confirm that the codes do not return and that symptoms resolve.

Note: Some CMP problems may require replacing the sensor or associated wiring harness, and certain vehicles may need dealer tooling or software updates to address timing or coordination between sensors.

What this means for vehicle owners

If you see a CMP-related code, it’s wise to get a professional diagnostic. A failed CMP sensor or damaged connector can cause stalling, no-start conditions, misfires, or reduced fuel efficiency, but misinterpreting data can lead to unnecessary part replacements.

Summary

Camshaft position sensor codes are a family of DTCs rather than a single universal code. The most common CMP-related codes are P0340, P0341, P0342, P0343, and P0344, though the exact code varies by vehicle. Diagnosis combines scanning, electrical testing, and timing checks to identify whether the sensor, its wiring, or the timing components are at fault. When in doubt, consult the vehicle’s service manual or a qualified technician to ensure accurate diagnosis and appropriate repairs.

How do I fix code P0340?

To fix P0340 code, first inspect and repair any damaged wiring or loose connections, as this is a common cause. If the wiring is good, replace the camshaft position sensor, and possibly the crankshaft position sensor, if it tests faulty. Other less common fixes can include repairing or checking the engine's timing chain or belt and, in rare cases, reprogramming the powertrain control module (PCM). 
This video demonstrates how to inspect the camshaft position sensor and its wiring for damage: 55s8020 AutomotiveYouTube · Sep 4, 2025
Step 1: Inspect and test the wiring and connectors 

• Visually inspect: Carefully check the wiring and connectors for any signs of damage, corrosion, or loose connections. 
• Clean: If you find oil or other buildup, clean the sensor and connections with a solvent or soap and water, as oil contamination can be a cause. 
• Tighten: Push any loose connectors to ensure they are fully seated. 
• Check fuses: Inspect the fuse that controls the sensor, as a blown fuse will cause this code. 
• Test the circuit: Use a multimeter to test the circuit voltage to ensure it is receiving proper power and ground signals. 

Step 2: Replace the camshaft position sensor 

• Locate the sensor: The camshaft position sensor is usually on the valve cover or near the cylinder head. 
• Perform a resistance test: Before replacing, test the sensor's resistance with a multimeter and compare it to your vehicle's specifications. If the reading is incorrect, the sensor is faulty and needs to be replaced. 
• Replace the sensor: Disconnect the battery, unplug the sensor, and install the new one. Be sure to transfer the O-ring and check that it is not left inside the engine hole after removal. 

This video shows how to replace a faulty camshaft position sensor: 1mWeeklyToolsYouTube · May 19, 2024
Step 3: Check the crankshaft position sensor and timing 

• Inspect the crankshaft sensor: The crankshaft position sensor works with the camshaft sensor, so inspect it for similar issues like damage or loose connections. 
• Inspect the timing components: Check the timing chain or belt for any issues or damage that could cause improper engine timing. 

Step 4: Final steps

• Clear the code: After making repairs, use an OBD2 scanner to clear the code from the vehicle's computer. 
• Test drive: Take the vehicle for a test drive to ensure the issue is resolved and the code does not return. 

When to seek professional help

• If you are unsure how to perform the tests or repairs, it is best to consult a professional mechanic. 
• If the problem persists after these steps, the issue could be a more complex one with the PCM or engine timing components that requires a professional diagnosis. 

How serious is the P0340 code?

The P0340 code is considered serious and requires immediate attention because it indicates a problem with the camshaft position sensor, which can lead to engine performance issues, difficulty starting, poor fuel economy, and potential engine damage if ignored. The vehicle should be diagnosed and repaired as soon as possible. 
Why it's serious

• Difficulty or inability to start: The vehicle may be difficult or impossible to start due to engine timing problems. 
• Poor engine performance: You may experience a rough idle, misfires, stalling, or a significant loss of power while driving. 
• Potential for engine damage: If the underlying cause is not addressed, it could lead to more serious and costly damage to other engine components over time. 

What it means

• The code indicates a malfunction in the camshaft position sensor "A" circuit. 
• This sensor is crucial for the engine's computer to accurately time fuel injection and ignition, and it also impacts other systems like variable valve timing. 

What to do

• Get it diagnosed immediately: Take your vehicle to a professional mechanic for a proper diagnosis and repair to prevent further complications. 
• Avoid driving if possible: While you may be able to drive, it is not recommended due to the risks of stalling and potential engine damage. 

What can throw a camshaft position sensor code?

A camshaft position (CMP) sensor code can be caused by a faulty sensor itself, problems with the electrical circuit (like broken wires or loose connections), or issues with the engine's timing components. Other potential causes include a damaged reluctor wheel, engine sludge affecting the sensor, or a failing powertrain control module (PCM). 
Sensor and circuit issues

• Faulty sensor: The sensor itself can fail due to age, wear and tear, or internal damage from heat or debris. 
• Wiring and connection problems: This is a very common cause. Issues can include broken wires, short circuits, loose connections at the sensor or PCM, or a poor ground connection. 
• Damaged reluctor wheel: The CMP sensor reads a reluctor wheel, which is part of the camshaft. If this wheel is damaged or cracked, it can send incorrect signals. 

This video explains the symptoms and causes of a bad camshaft position sensor: 42sCar Care CluesYouTube · Nov 6, 2024
Engine and mechanical issues

• Engine timing problems: If the timing belt or chain has jumped a tooth, the camshaft will be out of sync with the crankshaft, which the sensor will detect. 
• Engine sludge: Oil sludge or metal debris circulating in the engine can interfere with the sensor's operation. 
• Internal engine damage: More serious internal damage to the camshaft itself can also cause a sensor code. 

You can watch this video to learn how to test the camshaft position sensor: 58sECU TESTINGYouTube · May 16, 2023
Other less common causes

• Faulty PCM: In some cases, the powertrain control module (the vehicle's computer) may be failing, though this is less common. 
• Starter/battery issues: Problems with the starting system or a weak battery can sometimes lead to a CMP sensor code. 

How to reset camshaft position sensor?

You don't "reset" a camshaft position sensor, but after replacement, many vehicles require a "relearn" procedure to recalibrate the new sensor to the engine. This can be done by driving the car or using a diagnostic scan tool to perform a "cam crank relearn," which is often necessary if the engine control module (ECM) hasn't automatically recognized the new sensor. For some cars, a scan tool is required, and the process involves starting the engine once the ignition is on and letting the system complete the relearn automatically, often after the engine reaches a specific temperature. 
Methods to perform a camshaft sensor relearn
1. Drive the vehicle 

• For some vehicles, the relearn procedure may happen automatically simply by driving the car. 
• Start by clearing any stored diagnostic trouble codes after replacement. 
• Drive the vehicle normally to allow the engine control module (ECM) to adapt to the new sensor. 

This video explains what to do after replacing a camshaft sensor: 1m Easy Car ElectricsYouTube · Jun 20, 2023
2. Use a diagnostic scan tool 

• This method is often required for modern vehicles and may be more reliable. 
• Connect a diagnostic scan tool to the vehicle's OBD-II port and turn the ignition on without starting the engine. 
• Navigate to the ECM's special functions menu and select the "cam crank relearn" or a similar function. 
• The tool will prompt you to start the engine and then monitor the relearn process, which can be completed automatically or require you to reach a specific temperature (e.g., 70∘C70 raised to the composed with power cap C70∘𝐶 or 158∘F158 raised to the composed with power cap F158∘𝐹). 
• Follow the on-screen instructions until the tool indicates the procedure is complete.