You go outside to start your car and leave for work. When you turn the ignition, nothing happens. Besides being incredibly frustrated at being late for work, you may be scratching your head, trying to figure out what’s going on. You may not have had any signs of a problem, but now your vehicle isn’t going anywhere. A bad sensor could be the culprit.

Which sensors prevent the engine from starting?

Faulty sensors can keep your engine from starting as a safety measure. For instance, the crank angle sensor, or crankshaft position sensor, may be located near the transmission belt housing and come in contact with water, which would prevent it from working. This sensor measures the position of the crankshaft and the speed to ensure the pistons are timed for the right amount of combustion at the right time. If the information isn’t sent to the engine computer, nothing will happen when you try to start the car.

Another sensor that will impact whether your vehicle starts is the mass airflow (MAF) sensor. The function of this sensor is to let the computer know how much air is in the engine. As more comes in, more fuel is also needed to maintain optimal ratios. Without the correct ratio, the engine won’t run.

The oil pressure sensor on some models may prevent your car from starting if it isn’t working correctly. This sensor lets the computer know the correct oil pressure is present. If it sends a signal that the pressure is low, the computer may prevent the engine from starting. If the signal was sent in error or no signal sent at all, it may indicate you have a bad sensor.

Have a professional mechanic test your sensors if you think one of them is causing the problem. It can be replaced and you will be back on the road.

This article originally appeared on YourMechanic.com as Can a Bad Sensor Prevent a Car From Starting? and was authored by Joyce Morse.


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