The Top 5 Bad Crankshaft Position Sensor Symptoms

Modern vehicles are fitted with a series of different sensors that allow them to work seamlessly. One of the sensors we’ll be talking about is the crankshaft position sensor, which monitors the crankshaft’s rotational speed and position. 

The information from the crankshaft position sensor is sent to the ECU, so driving with a bad crankshaft position sensor will likely show some symptoms.

In this article, we’ll cover the top five symptoms of a bad crankshaft position sensor and what to expect regarding the cost of replacement.

The crankshaft position sensor is one of the most crucial components of any vehicle, as it directly affects how fuel injection and ignition timing work. Therefore, it’s important to know the symptoms of a bad crankshaft position sensor before you’re left stranded on the side of the road.

The top 5 symptoms of a bad crankshaft position sensor include:

• Check Engine Light
• Inability to start the car’s engine
• Reduced performance and fuel efficiency
• Engine stalling
• Rough idle and misfire

The Check Engine Light is a common symptom not just for a bad crankshaft position sensor but for every part of the vehicle connected to the ECU. As soon as the ECU notices any type of issue, the Check Engine Light will become illuminated, and the only way to know what’s causing it is to use an OBD scanner.

While checking for fault codes with your OBD scanner, look for the P0335 code, which suggests a faulty crankshaft position sensor. Unfortunately, the P0335 code doesn’t definitely mean that your crankshaft position sensor is faulty, but it will point you in the right direction in diagnosing the issue.

The crankshaft position sensor plays a pivotal role in the ignition system. It sends information about its position and speed to the ECU, which in turn dictates the ignition timing. Without proper information, starting your car is very unlikely, and even if you manage to get it running, it’s a matter of seconds before it stalls.

When a crankshaft position sensor is faulty, it doesn’t necessarily mean it’s not sending any type of information to the ECU. When the readings are wrong, the fuel injector timing is wrong, which equals a bad air-to-fuel mixture. 

When there’s a bad air-to-fuel mixture, the ECU will try and compensate by sending larger quantities of fuel to the injectors, wasting a part of the fuel and significantly reducing the vehicle’s performance capabilities.

A faulty crankshaft position sensor can cause different symptoms depending on the signals it is sending to the ECU. Faulty sensor readings cause poor fuel economy and performance, but if the crankshaft position sensor stops sending signals to the ECU altogether, your engine will stall almost instantly. 

When the crankshaft position sensor does not send a signal, the ECU assumes the engine is not running and completely cuts off fuel from the injectors.

Rough idle and misfires happen for the same reason why most of the other symptoms occur - a bad mixture of air and fuel. This is why you shouldn’t be driving with a bad crankshaft position sensor; it can lead to additional damage to the vehicle.

When the crankshaft position sensor sends inaccurate readings to the ECU, it can easily disrupt the balance of the combustion process. Wrong readings can cause incorrect ignition timing, incorrect fuel injection, and the loss of synchronization between the two, all of which lead to engine misfire and a rough idle. 

The crankshaft position sensor doesn’t fail very often, but when it does, there’s usually an underlying cause. The most common one is wear and tear.

The crankshaft position sensor is located close to the engine block, so it’s exposed to significant amounts of heat and vibration. Over time, heat and vibration can damage the sensor, causing it to send false readings to the ECU.

Another cause of a faulty crankshaft position sensor is damaged or corroded wiring. Although wires and connectors in the engine compartment are very well-insulated, time and heat exposure can damage the insulation, connectors, and wiring. This is why it’s recommended to visually inspect wires and connectors as part of regular car maintenance and replace any faulty wires or connectors as needed. 

A faulty crankshaft position sensor can be caused by human or manufacturer error. This means that improper installation or the crankshaft position sensor being faulty from the factory can be the underlying cause for your issues. Although it’s not so common, it can happen.

The crankshaft position sensor replacement cost depends on the year, make, and model of your vehicle, as well as whether you’ll be replacing the part yourself. If you take your vehicle to the mechanic, you can expect an estimate of up to $350 for labor alone. Surprisingly, given the importance of the crankshaft position sensor, it’s not as expensive as most would expect. 

Higher-quality replacement crankshaft position sensors from reputable brands start at around $15, while premium car brands and their flagship models require sensors that can cost up to $450.

PartsHawk’s selection includes hundreds of crankshaft position sensors and parts for various vehicle makes and models. It’s incredibly easy to find a specific part using the search bar or browsing parts by brand or vehicle year, make, and model.

Replacing the crankshaft position sensor requires only basic tools and DIY knowledge. Finding and reaching the crankshaft position sensor is the hardest part of the process while removing and replacing it with a new one is a matter of unbolting the old one and bolting the new one into position. If you’re unsure about replacing the sensor or your car is under warranty, make sure to get a certified mechanic to replace the part for you, as you might lose the warranty if you change the part yourself.