Camshaft Position Sensor Test (GM 3.1L, 3.4L)

Troubleshooting and testing the camshaft position sensor and diagnostic trouble code (DTC): P0341 CMP Sensor Circuit Performance, ( or DTC 17 if OBD I equipped) is one of the easiest tests on the planet! All you need is a multimeter and this article will take you step by step thru' the whole process. Although a scan tool is a great tool to have (and you should have one), it's not needed for the test in this article.

The test that I'm going to show you is a dynamic test done by hand cranking the engine. The camshaft position sensor can not be tested by doing a simple resistance test in Ohm's mode on your multimeter. The only way to test it and be sure of the result... a result that says: ‘YES, it's good or NO, it's bad’... is to test it dynamically, and I'll show you just how to do it.

To see if this cam sensor diagnostic tutorial applies to your specific vehicle, check out the ‘Applies To:’ box (on the right column).

The way this article is presented, is that you jump right into the test... but I recommend that you first take a look at the section entitled: How the CMP sensor Works.

Here are the contents of this article at a quick glance:

  1. Tools Needed To Test The Cam Sensor.
  2. Symptoms Of A BAD Cam Sensor.
  3. How Does The Cam Sensor Work?
  4. Circuit Descriptions Of The Cam Sensor.
  5. The GM 3.1L & 3.4L CMP Sensor Test.
  6. Interpreting The Results Of The Cam Sensor Test.
  7. Where To Buy The Cam Sensor And Save.
  8. More GM 3.1L, 3.4L Test Articles.

En Español You can find this tutorial in Spanish here: Prueba: Sensor De La Posición Del Árbol De Levas (P0341) (at:

Tools Needed To Test The Cam Sensor

You don't need any expensive tools to test the cam sensor on your 3.1L or 3.4L V6 engine.

Tools You'll Need:

  1. Multimeter.
    1. You can use a digital multimeter or an analog multimeter although the digital one is the preferred one.
    2. If you don't have a multimeter or need to upgrade yours, check out my recommendation here: Buying A Digital Multimeter For Automotive Diagnostic Testing (at:
  2. Jack.
  3. Jack stands.
  4. 1/2 inch ratchet wrench.

IMPORTANT: To test the cam sensor with the info in this tutorial, you'll need to jack up and place your vehicle on jack stands. Think safety and use common sense. Never trust the jack alone to hold up the vehicle!

Symptoms Of a BAD Cam Sensor

The most obvious symptom of a BAD cam position sensor is the check engine light, on your 3.1L/3.4L car or mini-van, will be shining nice and bright (with a cam sensor fail trouble code stored in the PCM's memory).

Below is a simple list of more specific symptoms that accompany a BAD cam sensor:

  1. BAD camshaft position sensor diagnostic trouble code (DTC):
    1. P0341 CMP Sensor Circuit Performance.
  2. Rough idle.
  3. BAD gas mileage.
  4. Your car or mini-van fails the state emissions test (smog check).

When the camshaft position sensor fails, it usually doesn't keep the car from starting. In other words... in the majority of the cases the car starts and runs (although it won't run like a champ).

How Does The Cam Sensor Work?

Camshaft Position Sensor Test (GM 3.1L, 3.4L)

The three wire camshaft position sensor, on your 3.1L or 3.4L equipped car or mini-van, is a Hall-Effect sensor.

Which in plain English means that it produces an On/Off DC voltage signal that can be measured with a multimeter, an oscilloscope, and even an LED Light.

In this article, I'm gonna' show you how to test the cam sensor (and thus code P0341) with a multimeter.

Now, in case you're wondering how the cam sensor works, in a nutshell this is what happens:

  1. The cam sensor gets power and ground as soon as you turn the Key and start cranking the engine.
  2. As the crank pulley turns, it induces the cam sensor to start producing an On/Off voltage pulse that is sent directly to the PCM.
  3. The PCM (Powertrain Control Module=Fuel Injection Computer) uses the camshaft position sensor to know when the cylinder #1 is at top dead center. This information is used to start pulsing the fuel injectors Sequentially (Sequential Fuel Injection mode).

The most important thing to know, is that the CMP will not keep the car or mini-van from starting if it goes BAD, although once started, it won't run right and will set a diagnostic trouble code (DTC) P0341.