What Does The CKP Sensor Do? (3.1L V6 Chevrolet And Pontiac Vehicles)

The crankshaft position (CKP) sensor is a very critical component of the ignition system of any vehicle. Depending on your specific 3.1L V6 Chevrolet (Pontiac), it'll come equipped with two of them.

In this article, I'll answer some of the most commonly asked questions about the 3X and 24X CKP sensor.

You can find this tutorial in Spanish here: ¿Que Función Tiene El Sensor CKP? (Vehículos Chevrolet y Pontiac Con Motor 3.1L V6) (at: autotecnico-online.com).

This tutorial applies to the following vehicles:

• 3.1L V6 Chevrolet Beretta: 1994, 1995, 1996.
• 3.1L V6 Chevrolet Corsica: 1994, 1995, 1996.
• 3.1L V6 Chevrolet Lumina: 1995, 1996, 1997, 1998, 1999, 2000, 2001.
• 3.1L V6 Chevrolet Malibu: 1997, 1998, 1999, 2000, 2001, 2002, 2003.
• 3.1L V6 Chevrolet Monte Carlo: 1995, 1996, 1997, 1998, 1999.
• 3.1L V6 Pontiac Grand Am: 1994, 1995, 1996, 1997, 1998.
• 3.1L V6 Pontiac Grand Prix: 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003.

How Many CKP Sensors Does My Car Have?

Depending on the model year of your specific 3.1L V6 Chevrolet (Pontiac), the ignition system on your vehicle will come equipped with one or two crankshaft position sensors.

If your vehicle is a 1995 or newer one, your vehicle's ignition system will have two CKP sensors. These two will be the 3X CKP sensor and the 24X CKP sensor.

If your vehicle is 1994 or older, then it'll come equipped with two CKP sensors only if it has California emissions.

If your 1994 (or older) vehicle comes with Federal emissions, it's only going to have a 3X CKP sensor.

If the engine comes equipped with two CKP sensors, it'll have these two:

• 3X CKP sensor.
  • Also known as the 7X CKP sensor.
  • Also known as the Low Resolution CKP Sensor.
  • Located on the side of the engine facing the firewall (it's the sensor in the photo above).
• 24X CKP sensor.
  • Also known as the High Resolution CKP Sensor.
  • Located on the timing chain cover and behind the crankshaft pulley.

If the engine comes equipped with only one CKP sensor, it'll only have a:

• 3X CKP sensor
  • Also known as the Low Resolution CKP Sensor.
  • Located on the side of the engine facing the firewall (it's the sensor in the photo above).

IMPORTANT: The 3X CKP sensor and the 7X CKP sensor are physically the same component.

What Do The CKP Sensors Do?

The 3X CKP sensor and the 24X CKP sensor have the job of monitoring the position of the crankshaft as the engine runs.

Specifically:

• The 3X CKP sensor's signal is used by the ignition control module so that it can activate the ignition coil packs (to begin firing spark to the spark plugs).
• The 3X CKP sensor's signal is used by the fuel injection computer to start injecting fuel.

Here are some more specifics:

• The 24X CKP sensor is connected directly to your Chevrolet (Pontiac)'s fuel injection computer and bypasses the ignition control module.
• The fuel injection computer uses the information from the 24X CKP sensor to calculate ignition timing when engine speed is under 2,000 RPMs.

What Happens When A CKP Sensor Goes Bad?

When either sensor fails, they'll simply stop monitoring the position of the crankshaft. This will result in the fuel injection computer or ignition control module not getting the signal from the bad CKP sensor.

If the 3X CKP sensor fails:

• The ignition control module will not activate the ignition coil packs.
• The fuel injection computer will not activate the fuel injectors.
• The end result is an engine that will not start due to lack of spark and fuel injection.

If the 24X CKP sensor fails:

• Then engine will usually start and run, but will have a rough idle.
• In some cases, the engine will not start.
• On OBD II equipped vehicles, the fuel injection computer may set a CKP sensor trouble code:
  • P0336: 24X CKP Sensor Circuit Problem
  • P1374: 3X CKP Sensor Circuit Problem

How Can You Tell If A CKP Sensor Is Bad?

The best way to find out if the 3X CKP sensor or the 24X CKP sensor is behind your vehicle's no-start problem is to test it (and make sure that it's producing a CKP signal).

Testing either sensor is not difficult at all, since there is a specific test procedure for each one.

In a nutshell, this is how the CKP sensor is tested:

• Check for CKP sensor trouble codes stored in the fuel injection computer's memory.
• Check that all 6 spark plug wires are sparking (if spark is present, then the 3X CKP sensor is OK).
• 3X CKP sensor:
  • Make sure that the 3X CKP sensor signal is producing an AC voltage signal as the engine is being cranked.
• 24X CKP sensor:
  • Make sure that the 24X CKP sensor signal is producing a DC voltage signal as the engine is being turned by hand.

I've written a tutorial that will help you test the 3X CKP sensor (also known as the 7X CKP sensor), you can find it here:

• Testing The Ignition Module and Crank Sensor (GM 3.1L, 3.4L).

You can find the 24X CKP sensor test here:

• How To Test The 24X Crankshaft Position Sensor (1995-1999 3.1L V6 Chevrolet Lumina, Monte Carlo) .

Can I Drive My Vehicle With A Bad CKP Sensor?

In the majority of cases, when a CKP sensor fails, the engine in your vehicle is not going to start.

In those instances that the engine does start, you should not drive your vehicle since you risk being stranded wherever the CKP sensor decides to stop working.

More 3.1L V6 Chevrolet, Pontiac Tutorials

You can find a complete list of 3.1L V6 Chevrolet (Pontiac) tutorials in this index:

• GM 3.1L Index Of Articles.

Here's a small sample of the tutorials you'll find in the index:

• How To Test A Blown Head Gasket (3.1L V6 Chevrolet, Pontiac).
• How To Test The Engine Compression (3.1L V6 Chevrolet, Pontiac).
• How To Test The Fuel Pump (1995-1999 3.1L V6 Chevrolet Lumina, Monte Carlo).