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How to Test 3 Wire Cam Sensor with Multimeter? Guide Of 2023

When your car starts acting up, one of the culprits could be a problematic cam sensor. This little device might seem insignificant, but it plays a big role in your engine's performance. It keeps an eye on the camshaft's position, making sure your engine runs smoothly. But what happens when it malfunctions? Your car might guzzle more gas, idle roughly, or even stall. You should learn the answer to “how to test 3 wire cam sensor with multimeter?” To determine if your cam sensor is the culprit, you can use a multimeter to check its power, ground, and signal wires. But here’s the big question: is it safe to do so?

Why Testing a 3-Wire Cam Sensor Matters?

Understanding why testing your cam sensor is vital can empower you as a car owner. This sensor ensures your fuel injectors and ignition coils work together correctly. When it malfunctions, it messes up this coordination, causing many problems. 

Testing the cam sensor with a multimeter helps confirm if it's getting power if the ground connection is solid, and if the signal it sends out is right. Early diagnosis through testing can save you from costly repairs later on.

Tools You'll Need for the Job

Before you start, gather the tools to make the process smooth and effective:

1-Multimeter: This handy tool measures voltage and current in your car's electronic circuits.

2-Back Probe Adapter (Optional): While not a must-have, this tool makes testing easier without disconnecting wires.

How to Test 3 Wire Cam Sensor with Multimeter: Step By Step

So, how to test 3 wire cam sensor with multimeter? Let's break down the process into easy steps to ensure you do it right:

Step 1: Get Your Car Ready

Safety first! Ensure your car is in park or neutral, and engage the parking brake. Always work on a stationary vehicle to stay safe.

Step 2: Find the Cam Sensor Connector

Locate the cam sensor connector, which is usually near the camshaft, often on the front side of the engine. Consult your car's manual if you're not sure where to look.

Find the Cam Sensor Connector

Step 3: Identify the Wires

Find the three wires: power, ground, and signal. Your car's manual will tell you which colors these wires are. Proper identification is essential.

Step 4: Set Up Your Multimeter

Switch your multimeter to DC voltage mode. This setting allows you to accurately measure the voltage in your sensor's wires.

Step 5: Check the Power Wire

Connect the multimeter's red lead to the power wire and the black lead to the ground wire. A working cam sensor should show your car's battery voltage, usually between 12-14 volts.

Step 6: Test the Ground Wire

Now, focus on the ground wire. Connect the red lead to the ground wire and the black lead to a stable ground source, like the engine block. A proper ground connection should read 0 volts.

Step 7: Look at the Signal Wire

Finally, check the signal wire. Connect the red lead to the signal wire and the black to the ground wire. Ask someone to start the engine while you watch the multimeter. A healthy signal wire will show a changing voltage, usually between 0-5 volts. If it stays constant, your cam sensor might be faulty. Now you know - how to test 3 wire cam sensor with multimeter?

Extra Tips for a Smooth Ride

  • Using a Back Probe Adapter: If you have one, testing simplifies as you don’t have to disconnect any wires, reducing the risk of mistakes.
  • Warranty Benefits: If your car's cam sensor is under warranty, consider having it tested at a local auto parts store or the dealership. Professionals can give you accurate results and save money if replacements are needed.
  • Stay Safe: Always be cautious When working around your car's engine. Don't touch moving parts, especially when the engine is running. Your safety should always come first.
  • Seek Professional Help: If you're unsure or uncomfortable about testing the cam sensor, don't hesitate to take your car to a mechanic. Their expertise ensures the right diagnosis and proper repairs, giving you peace of mind about your car's performance.

Signs of a Faulty 3 Wire Cam Sensor

Despite its small size, it plays a huge role in ensuring your engine works properly. If this tiny sensor goes haywire, it can cause significant issues, impacting your car's performance. 

Signs of a Faulty 3 Wire Cam Sensor

Recognizing the signs of a faulty 3-wire cam sensor can save you from big headaches and keep your engine running smoothly. In this detailed guide, we'll explore the indicators that suggest your cam sensor might be causing trouble.

1. Engine Misfires

The engine's rhythm gets disrupted when the cam sensor doesn’t do its job. This miscommunication leads to engine misfires, where the cylinders don’t fire in the correct order. Your car might start to stutter or run unevenly, indicating a potential problem with the cam sensor.

2. Decreased Fuel Efficiency

Your car's engine, when healthy, uses fuel efficiently. However, if the cam sensor isn’t working correctly, it messes up the engine's fuel combustion. This inefficiency means your car might burn more fuel than usual, causing your gas mileage to drop. If you make more pit stops at the gas station without an obvious reason, your cam sensor could be to blame.

3. Rough Idling

A well-functioning engine should run smoothly even when you’re not moving. However, a faulty cam sensor disrupts the engine’s idle speed, causing it to fluctuate. You might notice your car shaking or vibrating when it's standing still. This rough idling indicates that your cam sensor might need attention.

4. Difficulty Starting the Engine

Starting your car should be a smooth process. But your engine might have trouble starting up when the cam sensor isn’t doing its job. It struggles to find the right moment to inject fuel and ignite, making your car reluctant to start. If you turn the key multiple times before your engine roars to life, it’s a sign that your cam sensor needs checking.

5. Engine Stalling

The unexpected stop, called engine stalling, can happen due to a faulty cam sensor. When the sensor fails, it can't tell the engine what to do, leading to sudden halts, especially when idling or driving at low speeds. Engine stalling is not just inconvenient; it's also a safety concern that needs immediate attention.

6. Check Engine Light

Your car's onboard computer will notice if the cam sensor starts acting up. It will then trigger the check engine light on your dashboard. While this light doesn’t pinpoint the cam sensor directly, it signals that something within your engine system needs a closer look.

A failing cam sensor disrupts the engine's timing and fuel delivery, leading to a noticeable loss of power and acceleration. Your car feels heavy and unresponsive, struggling to pick up speed. If you feel a sudden drop in your car’s performance, it’s time to investigate the cam sensor.

7. Unusual Engine Sounds

But the engine's rhythm falters when the cam sensor isn’t working right. This can lead to strange noises like pops or backfires from your exhaust. These unusual sounds indicate that something is off in the engine’s combustion process, possibly linked to the cam sensor.

How to Check Camshaft Position Sensor with a Scanner? A Step-by-Step Guide

Your vehicle's camshaft position sensor is a critical component that monitors the camshaft's rotation. It plays a pivotal role in ensuring precise fuel injection and ignition timing. If this sensor malfunctions, it can lead to various engine issues. Using a scanner to check the camshaft position sensor is a quick and efficient method for diagnosing problems.

1. Prepare Your Vehicle

Before you begin the diagnostic process, ensure your vehicle is parked on a level surface with the engine turned off. Keep the gear in park (or neutral) and engage the parking brake for safety.

How to Check Camshaft Position Sensor with a Scanner

Navigate through the scanner menu to find the “Diagnostic Trouble Codes” (DTC) section. This menu allows you to check for error codes related to the camshaft position sensor.

2. Scan for Error Codes

Initiate the scanning process using the scanner. The device will communicate with the car's computer and retrieve any error codes in the system. If the camshaft position sensor is faulty, the scanner will display specific error codes indicating the problem.

3. Interpret the Error Codes

The scanner will provide alphanumeric codes, such as P0340, corresponding to specific issues. Look for codes related to the camshaft position sensor. These codes provide valuable information about the problem, aiding the diagnosis process.

  • P0340: Indicates a general camshaft position sensor circuit malfunction.
  • P0341: Specifies a camshaft position sensor "A" circuit range/performance problem.
  • P0342: Points to a camshaft position sensor "A" circuit low input.
  • P0343: Indicates a camshaft position sensor "A" circuit high input.
  • P0344: Specifies a camshaft position sensor "A" circuit intermittent.

4. Perform Live Data Monitoring

Some advanced scanners allow you to access live data from various sensors, including the camshaft position sensor. Navigate to the live data section on your scanner and locate the camshaft position sensor data. This feature lets you observe real-time sensor readings while the engine runs, providing valuable insights into the sensor's performance.

While monitoring the live data, start the engine. Observe the camshaft position sensor readings on the scanner. The sensor data should display consistent values corresponding to the camshaft's rotation. If the readings are erratic or show no change while the engine runs, it indicates a faulty camshaft position sensor.

5. Clear Error Codes (Optional)

Once you've noted the error codes and sensor readings, you can clear the error codes using the scanner. Clearing the codes resets the system and allows you to check if the issue persists after resetting. However, diagnosing the problem further before clearing the codes is essential to prevent overlooking any underlying issues.

If the error codes and sensor readings confirm a faulty camshaft position sensor, it's advisable to consult a professional mechanic for a comprehensive diagnosis and replacement. A mechanic has the expertise and tools to perform in-depth testing and ensure the new sensor is correctly calibrated, restoring your vehicle's optimal performance.


Testing your 3-wire cam sensor with a multimeter is a practical way to diagnose engine problems. Following these straightforward steps and keeping safety in mind, you can accurately assess your cam sensor's functionality. This knowledge empowers you to make timely repairs, ensuring your car runs smoothly and lasts longer. When in doubt, always trust the professionals for complicated car issues. We hope now you know “how to test 3 wire cam sensor with multimeter?”