Signs, Symptoms & What Causes Crankshaft Sensor to Go Bad –

1. Issues Starting the Vehicle

The most common symptom associated with a bad or failing crankshaft position sensor is difficulty starting the vehicle. The crankshaft position sensor monitors the position and speed of the crankshaft and other parameters that play an important role when starting the engine. If the crankshaft position sensor is having a problem, the vehicle may have intermittent starting issues or not start at all.


Difficult Starting or No Starting

It might be hard to get your engine started without the fuel it needs or without proper timing. If the crankshaft sensor has failed completely, and isn’t sending a signal to the ECU at all, then the computer won’t send any fuel to the injectors. This will leave you unable to start the car.

5. Engine Misfires or Vibrates

Should you feel or hear a brief stutter in the engine, it may be a sign of misfiring cylinders from a bad crankshaft position sensor. A failing crankshaft position sensor cannot provide the right information about piston positioning in the engine, causing a cylinder to misfire. This could also occur from faulty spark plug timing, but if the spark plug checks out, then the crankshaft sensor is likely the source.

What Can Cause A No Crank No Start?

In the case of an engine that refuses to start, it lacks ignition, fuel, or compression, as well as fuel. What was the problem? Was it running fine but then it ran fine but quit suddenly? Fuel pump failure, an ignition module failure, or a broken overhead cam timing belt are most likely to blame.

Why Crankshaft Position Sensors Fail In the First Place? 

There could be a number of reasons that a crankshaft sensor fails. We have some of the reasons below! 

Magnetic Issues 

The magnet, is a vital component for the crankshaft sensor, but it is prone to issues. The magnet can attract the smallest of metal debris or shavings created by engine friction. If those metal debris and shavings stick to the sensor or the wheel, they will thwart the sensor’s measurements. The metal debris can also begin a bridge to the wheel and the sensor.  Since your crankshaft sensor is designed to calculate the movements of the wheel at a certain distance the closeness will throw those measurements off. 

Wiring and Circuitry Issues 

The internal wires and circuitry that connect the crankshaft sensor to your car’s engine and power could be burnt out. Just one small short circuit is enough to cause huge problems with the crankshaft sensor. 

Burnt out sensors may cause the sensor miss receiving power. Furthermore, the sensor may not be transmitting a signal to the ECU.  

Crankshaft Position Sensor Function

The purpose of the crankshaft position sensor is t

The purpose of the crankshaft position sensor is to measure the position of the crankshaft. It might sound redundant, but it’s one of the most critical sensors in your vehicle. The crankshaft position sensor sends these measurements to the ECM, and the ECM uses them to optimize the rest of your vehicle’s timing.

If the crankshaft position sensor fails, then the ECM reverts to default values. While these values keep the engine running, you’ll likely notice various performance issues.

However, if the ECM doesn’t realize that the crankshaft position sensor has failed and is sending it errant measurements, the computer will optimize performance to inaccurate readings. This can quickly lead to more damage and expensive repairs.

Tachometer Doesn’t Work When Cranking

Since the tachometer essentially gets the RPM readings from the crankshaft position sensor, it can be a pretty clear sign if the gauge starts to malfunction. Generally, the RPM gauge does not give up altogether but it can be rather hard to judge if the readings are actually inaccurate when the vehicle is in motion. One way you could look to see a problem with the RPM gauge is when you crank the engine. 

The tachometer is not where most people would turn their eye when cranking the engine though it can be one thing to see when you have a prolonged crank. One of the purposes of the crankshaft position sensor is to measure crankshaft RPMs. So if the crankshaft position sensor is not working properly, it could cause your RMP gauge to not work.

Rough Idling

You might feel that the engine runs rough or vibrates at idle, say, when you’re sitting at a red light. This is similar to the above in that it stems from poor spark timing.

Is It Hard To Replace A Crankshaft Sensor?

A mechanic who has to perform a crankshaft sensor repair will spend a considerable amount of time removing the crank sensor, so as not to damage anything else. They can be a bit difficult to take off, due to sensor’s ability to get stuck in the block. The sensors also have a long stem, making removal difficult.  After the sensor has been taken loose, the mechanic will grasp it and begin the work of the repair. 

3. Fuel Economy Slippage

If your car crankshaft is not working optimally, one problem you’ll face is reduced fuel economy. The reason for this is that your vehicle’s fuel injectors won’t direct gas to the motor efficiently.

This means your motor will make use of more gas than is required when you’re out and about, which will result in lower fuel economy than normal. Of course, reduced fuel economy could be a function of other problems.

So it will be worth your while to go to an auto service center to have a professional assess the problem and to determine the right course of action.

Can A Bad Crankshaft Sensor Cause Loss Of Power?

A crankshaft sensor problem can also cause your engine to stall at low speeds, and the car will have difficulty starting when it is in motion. A faulty crankshaft sensor can also cause other engine problems such as rough idling, backfiring, and loss of power.

5. Check Engine Light On

While a check engine light won’t necessarily mean that your crankshaft sensor is failing, that doesn’t mean that this can’t be the case.

Because a check engine light could signal any of a number of problems, you’ll want to use a code scanning tool to figure out what triggered the check engine light. You can also go to an automotive service center.

Crankshaft Position Sensor Replacement Cost

The average crankshaft sensor replacement cost is between $150 and $250. However, it’s not uncommon for those prices to skyrocket if you have a higher-end vehicle.

That’s because the labor costs are typically between $90 and $110. From there, the rest of the cost comes down to parts. While most crankshaft position sensors cost under $100, there are a few out there that can blow through that price point.

Fortunately for most drivers, those more expensive parts are typically only on high-end luxury vehicles. If you’re looking to save a few bucks, you can replace the sensor yourself. It’s a pretty straightforward job if you can reach the sensor.

While this is only going to save you about $100, if you’re a little mechanically inclined, you can complete the entire job in under 30 minutes.

There are actually some car models, even if it is very rare, but they can be located behind the flywheel, so you have to remove the gearbox to replace the sensor.

Most Common Signs of a Failing Crankshaft Position Sensor

When a crankshaft position sensor is bad or failin

When a crankshaft position sensor is bad or failing, it will give a series of signs that you can identify and diagnose your vehicle. To be absolutely sure about your diagnostics, you will need a scanning tool. (check prices on Here are the 5 most common signs of a failing crankshaft position sensor:

1. Vehicle cannot start

The crankshaft position sensor is part of the timing system. It monitors the speed of the crankshaft and its position. When the piston reaches to top dead center, the crankshaft position sensor sends information to the ECU, and the ECU coordinates with the ignition and fuel injection system.

When the crankshaft position sensor fails, simply due to normal wear and tear, obstructions, or interference it cannot perform its duties. Meaning, a faulty crankshaft position sensor can no longer send accurate information about the position of the piston and the computer will not spray fuel into the engine.

2. Vehicle stalls while driving

When the crankshaft position sensor is failing, it can cause intermittent stalling. The vehicle may stall at all speeds. The ECU will not receive any reliable signal from the crankshaft position sensor, therefore, interfering with the timing system. At this point, the engine may shut off at any time due to lost timing signal. Simply, the ECU will no longer spray fuel into the engine and your engine will shut off.

3. No fuel injection pulse

No fuel injection pulse is a sign of a failed crankshaft signal. The crankshaft sensor sends a signal to the ECU and the ECU determines when the fuel injector should spray fuel into the engine and how much.

It’s best if you use a scanning tool and run diagnostics on your vehicle. The scan tool will tell you exactly what is wrong with your vehicle.

4. No RPM movement while cranking

If the RPM needle on your dashboard is not moving while you are cranking your vehicle, this means there is no crankshaft signal. This symptom will not apply to all vehicles, but you can combine it with some of the previous symptoms and determine if your crankshaft position sensor is faulty.

5. Interference from

A broken timing chain, broken timing belt, broken harmonic balancer, and open wires can cause premature wear and failure to the crankshaft position sensor. A broken timing belt will damage the crankshaft position sensor and the interference engine.

Make sure the crankshaft position sensor is not wet from engine oil that could be leaking from the front seal or crankshaft seal. Also, check for coolant leaks from the water pump.


Many a time, while testing for a bad crankshaft position sensor, the scanner can read you a dozen other problems, whereas sometimes you may not find a fault with the sensor yet experience the symptoms.

That’s because the sensor itself may be fine and in complete working order but the signal being passed cannot effectively be transmitted to the engine control unit due to a breakage in the path.

There’s a labyrinth of electrical work and fuses that go under a vehicle, so be sure to check if there isn’t a chapped wire or a loose plug somewhere as it can produce much the same result and lead your engine computer to believe, the sensor has gone bad.

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