The 8 most common reasons why your car will not start.

Published: 09/06/2023


It is a heart sinking moment when you turn the ignition key and are not met with the familiar hum of the engine.

Your car won’t start.

There is a moment of disbelief, made worse by realization that the deadlines of work, school or waiting children will now not be met.  There are a number of reasons why your car wont start. Some of these are short term inconveniences with simple solutions and others are more difficult and require a trip to your friendly mechanic. 

Here is a helpful list of the 8 most common reasons why your car won’t start.


Faulty, flat, or dead battery

A dead battery is probably the most common reason for a car not to start. The tell tale rapid clicking noise that is heard when you start the ignition is typical of this fault. It could be that the battery is simply drained flat of all power. It could be a fault in the battery connections, or it could be a mechanical fault. Open the bonnet and make sure that the negative and positive cables are firmly attached to the battery terminals. If its just a loose connection, the car may well start again. The signs that a battery is dying and a new one might be needed can include the dim of flickering tail lights and dimming interior lights. If the battery has just been drained by something simple, like the lights left on you can jumpstart the car. Jumper cables can be used to jump start your vehicle. If you have never jump started a car, follow the instructions here. Once the car has received the jump of power to start again from your friendly ‘donor car’. It will charge up as you drive normally again.


Alternator problems

The alternator keeps the battery charged. A faulty alternator means that your car is getting no power. If your car starts, but then stops immediately, the problem could be the alternator. If a jump start gets it going again but the problem of non-starting persists, then a completely dead battery or broken alternator maybe the issue. There should be an electrical system warning light on the dashboard letting you know that there is a problem. It can be difficult to know whether your problem is a battery or an alternator issue, as they present with similar symptoms. Check the battery first and if all is well with the cables and the battery itself, ask your mechanic to check the alternator.


Starting Motor

If the key turns, the car cranks but it just wont start, it may be the starting motor. You may hear a loud click when you turn the key in the ignition or press the start button. The starting motor begins the process of getting a spark to ignite the fuel in a diesel or petrol engine car.  When the starting motor is not getting that spark to where it needs to go, then it just will not start. It could also be an electrical circuit issue such as a bad earth connection. Your friendly garage will need to assist at this stage.


Fuel Problems

Faulty or clogged fuel injector nozzles can stop fuel from getting to the engine. This is not something that happens overnight, and you may have been ignoring an engine warning light prior to this clogging happening. There may have been a loss of power while driving too. Your local friendly garage will help with this problem, but it makes sense to get to the garage before the car is affected so badly that it won’t start. Running out of fuel is an obvious reason for your car not starting. If you are one of those people who likes to dice with fate and drive on the fumes of your fuel for a while, it is worth noting that quite apart from the chance of stopping on the road, this is a more expensive way to drive. If you have put the wrong fuel in your car, and it has stopped and will not start again, then call your garage as a matter of urgency.


Fault immobiliser

It’s a bad day when your car does not start, but when your car's own security system prevents the engine from starting it is a step further. When the key fob has a flat battery, the car cannot be started. If the immobiliser fails to recognise your key, then your engine won't start at all. A new battery in the fob will solve the issue.


Engine problems

Engine problems can prevent your car from starting. This may include timing belt, timing chain or crankshaft issues. The vehicle is likely to have had a warning light or some odd behaviour before it got to the stage where it would not start. It is a mechanical problem that needs proper investigation and repair.


Jammed ignition or steering lock

If your steering wheel is locked, you may be unable to start the car. Ether your ignition switch won't turn or, if your car has a start-stop button, you'll see a warning light about the steering lock. Usually this can be solved with a few simple steps to free it up. Wiggle the steering wheel slightly to see if it loosens but be careful not to force it. Moving from left to right can free the lock. Never force the key to turn or you may break it and they are very expensive to replace. You can often free a jammed lock yourself without needing a mechanic.


Low AdBlue

If you have a diesel car that requires it, and you regularly use AdBlue to help reduce emissions, it is important that you keep it topped up. Running out of AdBlue will cause your car to stop. Most cars will display a dashboard warning light when the AdBlue is starting to run low and this usually lights up when there are three litres of fluid left, giving you plenty of time to add more.

A car that wont start is a real nuisance and a worry to any motorist. Regular servicing and attention to the little hints of wear and tear or niggling problems can help avoid that dreaded non-start day. 

Here at Peter Hanley Motors, we are always on hand to advise and assist so that your car starts first time and every time.

Peter Hanley Motors is a registered
member of The Society of the Irish
Motor Industry

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