Blog Car Care Advice 6 Bad Crankshaft Position Sensor Symptoms (+ How to Confirm)
Car Care Advice

6 Bad Crankshaft Position Sensor Symptoms (+ How to Confirm)

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Does your engine stall frequently or doesn’t start at all?
Well, the crankshaft position sensor (CKP sensor) could be to blame. 

The crankshaft position sensor has a crucial role in fuel injection and ignition timing. If it breaks down, it could lead to issues like engine misfire, poor acceleration, or low gas mileage.

Bottom line: You need to replace it ASAP

We’ll cover the six bad crankshaft position sensor symptoms you need to watch out for and why driving with a faulty crankshaft sensor could be risky. We’ll also tell you ways to prevent sensor damage and save repair costs. 

This Article Contains 

6 Bad Crankshaft Position Sensor Symptoms You Shouldn’t Ignore

Here are six signs that point to crankshaft position sensor failure: 

1. Active Check Engine Light 

Even though the check engine light doesn’t directly mean that your crankshaft position sensor is faulty, it indicates something is amiss. 

A crankshaft sensor detects the position and speed of your engine’s crankshaft. If this sensor malfunctions, it may send incorrect or no data to the Engine Control Unit (ECU) or the Engine Control Module (ECM). 

When that happens, the ECU will trigger the check engine light on your dash and register a trouble code related to a faulty crankshaft, camshaft, or camshaft sensor. 

2. Trouble Starting the Vehicle

An internal combustion engine requires fuel and a spark to generate power.

If the ECU or ECM doesn’t receive any sensor signal from the crankshaft position sensor, it won’t know when to pulse the fuel injectors and ignite the spark plug set. This will lead to difficulty in starting the engine

3. Engine Stalling 

A faulty crankshaft position sensor could lead to engine stalling while driving or at idle

So, even if your vehicle manages to start, the mismatched fuel injector and ignition timing (spark timing) could leave you stranded on the road. This can be particularly dangerous while driving in heavy or fast-moving traffic. 

4. Excessive Engine Vibrations 

When there is no sensor signal, your engine and the crankshaft will be out of sync. This lack of synchronicity can result in severe rattling or juddering under the hood. 

Note: The engine vibrations may settle intermittently when the engine and the crankshaft line up accidentally. 

5. Poor Acceleration and Engine Misfire

A faulty crankshaft sensor that affects the fuel injector and spark timing (ignition) will often result in too much or too little gas in the internal combustion chamber. This can manifest as loud misfires

This will also cause the engine to sputter when you accelerate

6. Reduced Gas Mileage 

The lack of proper fuel injection will cause your engine to work harder to generate power. Consequently, it’ll consume more fuel than it usually does, reducing your fuel economy. 

That said, the above signs are not exclusive to a bad crankshaft position sensor, making it difficult to diagnose the real issue.

Let’s find out how you can confirm you have a faulty crankshaft position sensor. 

How to Diagnose a Bad Crankshaft Sensor?

Since accessing and inspecting the crank sensor can be tricky, it’s best to take your vehicle to an expert mechanic. They’ll perform a series of tests to diagnose the problem. 

Here’s how a mechanic would check for a bad crankshaft position sensor:

A. Run a DTC Scan

Because a check engine light can mean many things, they’ll need to check what exactly triggers it. 

If the check engine light is on, the mechanic will use an OBD2 scan tool to read the trouble code registered by the ECU. A failing crankshaft position sensor will likely throw a P0017 or P0335 code along with other codes related to misfires and ignition timing. 

B. Visual inspection

If the engine light is active due to a bad sensor, they’ll check the sensor, its wiring, and connectors for any physical damage or corrosion. They’ll also check the gap between the sensor tip and the reluctor ring. 

The reluctor ring is a toothed ring on the crankshaft. It passes by the CKP sensor to signal the crankshaft’s position to the ECU. The gap between these two parts should be precise, as listed in the owner’s manual. 

C. Check the Sensor Function

They’ll use a multimeter to check the output signal from the sensor. It should go from 0 to 5 volts when you crank the engine. If it’s outside the specified range, it indicates a failing crankshaft position sensor that should be replaced.  

If you plan to put off this replacement, this can be risky. 
Keep reading to find out why. 

Is it Safe to Continue Driving with a Bad Crankshaft Sensor?

In most cases, you’ll be unable to start your car if you have a faulty sensor, so you’ll need to replace it immediately. 

And even if you manage to crank up your engine, driving with a bad crankshaft sensor and an active engine light could result in: 

So, it’s best to address the crankshaft position sensor symptoms promptly and get a replacement if needed. 

Let’s also find out the cost of replacing a crank position sensor. 

How Much Does Crankshaft Sensor Replacement Cost?

The replacement cost of a crank position sensor can range from $100 to $500. The part can cost between $20-$200 and the labor charges can vary depending on where you live. This cost can also vary depending on the vehicle’s make and model. 

Tip: Always use a crankshaft position sensor compatible with your vehicle. An incompatible part could impact your engine performance. 

With the basics sorted, let’s also address some additional queries. 

4 FAQs on Crankshaft Position Sensor

Here are answers to common crankshaft sensor-related questions: 

1. What Does a Crankshaft Position Sensor Do?

The crankshaft position sensor monitors the rotational speed and position of the crankshaft in an internal combustion engine. It, along with the camshaft position sensor (cam sensor), provides crucial data to the Engine Control Unit, enabling accurate control of ignition timing and fuel injection to match engine speed.

In some vehicles, the sensor also helps the Engine Control Module manage the variable valve timing system if the vehicle is equipped with it.

2. What Causes Crankshaft Position Sensor Failure?

The crankshaft position sensor can malfunction and trigger the engine light due to: 

3. Can I Temporarily Fix the Crankshaft Position Sensor?

Unfortunately, no.

The crank sensor should always operate at 100% capacity to maintain the correct engine speed and engine performance. If you’re experiencing bad crankshaft position sensor symptoms, get it replaced ASAP.

4. How Can I Prevent Crankshaft Sensor Malfunctions?

Here are some tips to keep your CKP sensor in good shape for longer: 

Check Your CKP Sensor to Keep Your Engine Purring 

Recognizing early warning signs of a crankshaft position sensor problem can help prevent unexpected breakdowns and costly repairs. If you suspect you have a faulty sensor, you must replace it at the earliest.

And for that, you can hire an expert from AutoNation Mobile Service.
We’re a mobile auto repair service available seven days a week and we offer a 12-month, 12,000-mile warranty on all repairs. 

Contact us today for a quote.