Get your car sensors fixed

Modern cars have dozens and sometimes even hundreds of sensors to monitor their performance and environment. These include oxygen sensors, mass air flow (MAF) sensors, oil pressure and level sensors, parking aid sensors and many more. Unfortunately, it isn’t uncommon for sensors to malfunction due to old age, electrical issues or contamination. 

Sensors are essential for the operation of the engine control unit (ECU). Without them, the ECU doesn’t have the information required to keep your car running optimally, so you should consider booking a repair sooner rather than later.

How much does a sensor replacement cost?

The price of a sensor replacement varies depending on numerous factors, one of the most significant being the sensor's location. The harder it is to reach and the longer it takes, the more expensive the repair will likely be. 

The average price of a general sensor replacement is £76.84. You can see how the price varies between different car makes in the table below.

According to FixMyCar’s data, the cheapest type of sensor to replace is an ABS sensor, which costs £73.20 on average; the most expensive is a DPF sensor, costing £129.64.

How do sensors work?

Sensors are electronic devices that monitor different aspects of a vehicle. They send information to the engine control unit, which may make adjustments accordingly or notify the driver of a change.

One way to understand sensors is to think about your senses - hearing, taste, smell and touch. When you pick up something hot, nerves in your fingers signal to your brain that you should put the hot thing down to avoid hurting or damaging yourself. A similar process happens in cars.

What are the different sensors in a car?

Here are a few of the most important sensors.

Crankshaft sensor

The crankshaft is responsible for converting linear motion into rotational motion to turn the wheels. A crankshaft position sensor monitors the speed and position of the crankshaft and sends this information to the ECU. 

DPF sensor

A diesel particulate filter (DPF) differential pressure sensor monitors exhaust backpressure (the exhaust gas pressure produced by the engine to overcome the hydraulic resistance of the exhaust system to discharge gases into the atmosphere) and signals to the control unit when it’s time to start a regeneration cycle to clear the DPF of soot.

Find out how to avoid DPF problems.

Fluid pressure sensors

Fluid pressure sensors include oil pressure sensors and fuel pressure sensors. As the name suggests, these types of sensors monitor the pressure of various fluids, sending signals to the ECU if they are too low.

Camshaft sensor

The camshaft sensor monitors the position of the camshaft, which opens and closes the valves at the top of each cylinder. To ensure injector synchronisation, the ECU uses this information to determine which cylinder is firing. 

Oxygen or lambda sensor

The oxygen sensor - also known as the lambda sensor - monitors how much unburned oxygen is in the exhaust. The ECU uses this information to ensure the correct air-fuel ratio is sent to the combustion chamber, preventing the car from running rich or lean.

Tyre pressure sensors

Tyre pressure sensors monitor the air pressure inside a car’s tyres; when it drops too low, the ECU triggers a warning light telling the driver to top them up. 

Mass air flow sensor

The mass air flow or MAF sensor monitors the amount of air entering the engine; based on this, the ECU calculates how much fuel is needed to maintain the correct air-fuel ratio.

Symptoms of car sensor failure

The symptoms of sensor failure are wide-ranging. For an oxygen sensor, which sits in the exhaust system, you’re likely to experience poor performance, increased fuel consumption, rough idling and engine misfires. 

On the other hand, faulty ABS wheel speed sensors are often accompanied by a loss of traction, failure of the ABS, a pulsating brake pedal and an illuminated ABS dashboard light.

When an oil pressure, fluid level, or tyre pressure sensor fails, you can often tell because a warning light will incorrectly appear on the dashboard due to the ECU receiving false information.

Learn more about sensors

• Tyre Pressure Sensors: How They Work & How to Reset Them

• What Is a Lambda Sensor and What Does It Do?