How Camshaft Position and Crankshaft Position Sensors Impact Engine Operation

Sensors In Your Vehicle

From tracking car functions to improve safety to monitoring the engine to optimize performance, sensors are critical to the operation of modern vehicles. They relay data to the vehicle’s Electronic Control Unit (ECU), which can make real-time adjustments or take emergency actions.

In a vehicle with an internal combustion engine, there are several sensors that track and maintain engine function, including the ignition process. Two sensors are crucial for ensuring the ignition process properly powers the vehicle – the camshaft position sensor (CMP) and the crankshaft position sensor (CKP).

What Does the Camshaft Position Sensor Do?

As the camshaft rotates, the camshaft position sensor records its position. This information helps the ECU synchronize the opening and closing of the engine’s intake and exhaust valves with the corresponding position of the piston. The ECU uses data from the camshaft position sensor to optimize spark timing and fuel injection, ensuring efficient engine performance.

What Does the Crankshaft Position Sensor Do?

The crankshaft position sensor detects the precise position of the crankshaft. It does this by measuring the rotation speed (RPMs). As the crankshaft rotates, the sensor produces a pulsed voltage signal. Each pulse corresponds to a tooth on the reluctor ring. The ECU uses this signal to calculate ignition timing, fuel injection timing and engine RPM. The crankshaft position sensor also helps monitor individual cylinder misfires. The engine needs a properly functioning crankshaft sensor to deliver optimal performance.

How Do the Camshaft Position and Crankshaft Position Sensors Work Together?

The information from the camshaft position and crankshaft position sensors tells the ECU when a piston is at top dead center and ready for the intake stroke of the combustion process. The information provided tells the ECU that the valve timing is correct to deliver the air and fuel necessary for combustion. Working together, these sensors tell the ECU when conditions are right to initiate the combustion process.

Signs of a Failing Camshaft Position Sensor or Crankshaft Position Sensor

A failing or malfunctioning camshaft position sensor or crankshaft position sensor can lead to drivability issues. You may have problems starting the vehicle, it might crank but not turn over or the engine may stall or stutter. Poor acceleration or declining gas mileage are other signs that there is an issue with a camshaft or crankshaft sensor. In addition, the check engine light might become illuminated. 

Because each of these symptoms can be related to problems besides a bad camshaft or crankshaft sensor, it is imperative to have your vehicle examined by an auto technician if you notice any of these signs of a failing camshaft or crankshaft sensor.

What Causes a Camshaft Position Sensor or Crankshaft Position Sensor to Fail?

Camshaft position or crankshaft position sensors can fail for a variety of reasons:

Can You Drive with a Bad Crankshaft Sensor or Camshaft Sensor?

If you suspect that you have a failing camshaft or crankshaft sensor, you should have your auto technician examine your vehicle. Continuing to drive with a bad camshaft or crankshaft sensor, it can cause issues for your vehicle:

Decreased Engine Performance – With both sensors designed to ensure the engine functions properly, if either fail it can cause drivability issues like hard starts, rough idling or stalling.

Damage to engine parts – If either of these sensors are bad it can disrupt the conbustion process and cause damage to additional engine parts. This can lead to additonal repairs down the road.

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The content in this article is for informational purposes only. You should consult with a certified technician or mechanic if you have questions relating to any of the topics covered herein. Tenneco will not be liable for any loss or damage caused by your reliance on any content.