Why does my car fail to start in the morning

The process that goes on from the moment you put the key into the ignition to the point where the engine is running involves a few steps. Once you know at which step things go wrong, you will have a better idea why your car will not start and what to do. File Photo

What you need to know:

  • A bad intake air temperature sensor can to a certain extent do the same.

My car fails to start in the morning, why? Eric

That is called a cold hard start condition. There are several causes of cold hard starting in the morning. The most common ones are a faulty engine coolant temperature switch (sensor) which helps the engine management system perform cold start enrichment which runs the engine faster to help warm it up until its stable enough to idle at lower revs.

A bad intake air temperature sensor can to a certain extent do the same. A malfunctioning idle air control (IAC) valve will also cause hard cold starts as it is not able to bypass the throttle unit and provide enough air to stabilise the engine during cold starts. Leaking vacuum and EGR unit will also cause hard cold starts.

Insufficient fuel delivery pressure caused by a clogged fuel filter or dirty injectors can also cause hard cold starts.

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