Symptoms of a bad crankshaft position sensor

8/18/24

Your engine’s major components and systems require communication with one another, and the crankshaft position sensor generates data necessary for this process. It monitors the crankshaft’s position and speed during rotation so systems like fuel injection and ignition can be perfectly timed. The crankshaft position sensor, typically positioned externally at the bottom of the engine block near the crankshaft pulley or the flywheel, detects teeth or markings that rotate past it, then sends a reading to the engine control module to indicate where the crankshaft is on its rotation.

In this article, learn more about the symptoms you will experience with a bad crankshaft position sensor, the reasons it can fail, and what can be done to determine that it’s bad.

What are the symptoms of a bad crankshaft position sensor? 

When a crankshaft position sensor fails, it can be either an intermittent or a constant issue. You might experience one or many of these symptoms at the same time.

Check Engine Light comes on 

The engine control module can see when the crankshaft position sensor’s readings aren’t within normal values, and it turns on the Check Engine Light to indicate there’s a problem.

Difficulty starting the engine 

The ignition timing or fuel injection timing may not be correct when you try cranking the engine over, and the engine may not start as a result.

Stalling 

When the crankshaft position sensor signal is lost while driving, it can cause the engine to stall.

Lack of acceleration 

Incorrect or inconsistent timing due to timing issues can cause poor combustion, resulting in poor acceleration.

Decreased fuel efficiency 

If the crankshaft position sensor is reading sporadically, the fuel may not combust in the engine as it should. Lower power production requires that more fuel is consumed to achieve the same performance you need.

Exhaust smells 

Inefficient combustion allows unburned and partially burned fuel to enter the exhaust system, and as it reacts in the catalytic converter, the exhaust smell becomes much stronger.

What causes a crankshaft position sensor to fail? 

There are some common causes of a crankshaft position sensor failure including:

• Wiring problems – The sensor’s wiring may be rubbed through, cut, or cracked.
• Sensor damage – Impact to the sensor can break it, and exposure to its high-heat environment for many years can contribute to failure.
• Reluctor wheel issue – The reluctor wheel, which the crankshaft position sensor monitors to produce its reading, may be damaged, dirty, or wobbling, causing the sensor to become damaged or producing an inconsistent reading.
• Corrosion – The wiring connector may have water introduced into it, and corrosion that forms can damage the pins or wiring, or corrosion can interrupt the connection between the sensor and the harness.

How to diagnose a bad crankshaft position sensor? 

A crankshaft position sensor provides extremely precise readings to the engine control module, and if the sensor isn’t operating properly, a thorough diagnosis needs to be performed. This helps determine whether it’s the sensor that’s faulty, if it’s a poor wiring connection, or another issue that could look like the sensor has an issue.

• Check for trouble codes. With a diagnostic scan tool, you can check the engine control module for codes that point you toward a faulty crank sensor. The description may be related to the crankshaft position sensor, or CKP sensor, or it might be more generalized such as an engine misfire or a timing-related code.
• Inspect the wiring. There may be an obvious break in the wiring at the sensor or a disconnected connector.
• Test the sensor. In many cases, a faulty sensor can be found by testing the resistance. To complete a test like this, you will require a multimeter.

Also, it’s possible that the sensor has become dirty. If there is oil or dirt on it, you won’t get an accurate reading since it can’t ‘see’ the reluctor wheel. Sometimes, removing the sensor and gently cleaning it can help.

Special tools and knowledge are required to accurately diagnose the crankshaft position sensor. If you don’t have the equipment or you aren’t completely comfortable performing the repair, a trusted mechanic can do it for you.

Buy a new crankshaft position sensor at TRODO 

Whether you are replacing it yourself or having a repair garage complete the job for you, get your new crankshaft position sensor from TRODO. Here you’ll have access to parts from many of the best-known brands including Bosch, Denso, HELLA, and more, with options for almost any car make and model you may drive. Choosing the correct part for your car is easy by entering additional information to select the perfect compatibility. For your peace of mind, request a free compatibility check by our in-house experts.

Frequently asked questions:

Can a faulty crankshaft sensor cause engine failure? 

There’s no immediate danger of engine failure if the crankshaft position sensor fails. However, if you continue to drive it for an extended period, it’s possible that long-term damage could occur from the improper combustion that’s occurring. It’s best to address problems right away.

How do I know if my crankshaft position sensor is bad? 

The most common symptom is the Check Engine Light coming on with crank sensor-related trouble codes. As well, you may notice decreased power, stalling or stumbling, poor acceleration, and poor fuel efficiency. These symptoms could be constant or intermittent.

Will my car run with a faulty crank sensor? 

It depends on the severity of the issue. If the crankshaft position sensor is losing signal intermittently, the car may run and drive poorly. If the sensor fails completely, it’s unlikely it will start at all.

What are the common causes of a bad crankshaft position sensor? 

The most common causes include corrosion on the connector, damaged wiring, or physical damage to the sensor itself.