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Turning the key - or pressing the start button - and getting no response is one of the most frustrating experiences a driver can have. Whether you’re in a rush for work, heading home, or parked outside the shops, it can feel like a nightmare, whatever the cause. Below, we look at ten of the most common reasons a car won’t start, what you can check for yourself, and when it is time to call the experts.
Flat or weak battery
A flat battery is easily the most common reason a car won’t start. If you hear a clicking sound when turning the key, notice that the dashboard lights are dim or they flicker and fail to come on, the battery is the prime suspect.
Why it happens:
- Leaving lights or in-car accessories switched on
- Cold weather reducing battery efficiency
- Battery reaching the end of its lifespan (usually 3-5 years)
What you can do:
Try jump-starting the car if you have jump leads. If the car starts, but struggles again later, the battery may need recharging or replacing.
Faulty starter motor
If the battery is healthy but the engine will not turn over, the starter motor could be to blame. This is the component that physically turns the engine when you start the car.
Common signs include:
- A single loud click when turning the key
- No sound at all
- Intermittent starting problems
If this is happening on a regular basis, the starter motor usually needs replacing and should be assessed by a professional garage.
No fuel
Running out of fuel - or struggling to get it to the engine - is more common than many drivers realise, especially if the fuel gauge is inaccurate. If you’re having starting problems, consider:
- Are you relying on the “miles remaining” display?
- Has your car been parked on a steep incline, causing fuel to move away from the pickup pipe?
If there is fuel in the tank and the engine still won’t start, there may be a problem elsewhere in the fuel system - a diagnostic check from an expert may be the smart call here.
Fuel pump problems
If you’ve recently filled up and are still having problems, there could be an issue with the pump that delivers fuel from the tank to the engine. If it fails, the engine won’t receive the fuel it needs to start.
Signs include:
- The engine cranking, but failing to fire
- A whining noise from the rear of the car
- A sudden loss of power from the last time you drove the car
A fuel pump problem requires specialist diagnosis and repair - losing power mid-drive is not a risk you can take.
Ignition switch or immobiliser issues
Modern vehicles use coded keys and immobiliser systems to reduce the risk of theft. If there is a fault with these failsafes, the engine may not start, even if everything else appears normal. Possible causes include:
- A worn ignition switch
- The key has become damaged or deprogrammed
- A fault in communication between the immobiliser and your car
Most cars now come with two keys so you have a spare. If you do, try using it instead. Persistent issues should be checked using specialist diagnostic equipment.
Worn spark plugs or ignition coils
Petrol engines rely on spark plugs to ignite the fuel-air mixture that gets your car moving. Over time, these components can wear out.
Warning signs:
- Difficulty starting, especially in colder weather
- Engine misfires, then fails to start
- Reduced fuel economy - you’re getting less distance before needing to refill
Replacing spark plugs is part of routine servicing and can prevent more extensive starting problems.
Blocked fuel filter or injectors
Fuel needs to flow into the engine in a clean and consistent manner. This usually happens automatically but a blocked fuel filter or dirty injectors can lead to a restricted flow. Common causes are:
- Poor quality fuel
- Long periods without driving
- General wear and contamination
It is recommended that these elements are cleaned professionally or replaced completely if necessary to restore proper performance. The issue may be recognised initially by a breakdown mechanic, but may need to be repaired at a garage.
Alternator failure
Your battery rarely requires manual charging because the alternator converts energy from driving to keep it charged. If it fails, the battery will slowly drain even if it is relatively new. Signs that your alternator may be in trouble include:
- Battery warning light on your dashboard
- Electrical issues: flashing lights or glitchy display on in-car screens
- The car may jump-start, but won’t stay running
This is a fault that needs to be addressed quickly. Without a viable alternator, any battery will quickly drain and the car will be unusable.
Sensor or ECU faults
Modern cars depend on sensors, such as crankshaft or camshaft sensors, to manage engine timing, and the Engine Control Unit is essential to keeping things moving. If these onboard components aren’t working, the signs may include:
- An engine turning over but failing to start; noticeable by a repeated grinding noise
- Warning lights on the dashboard
- Starting issues that are intermittent to begin with and worsen over time
These faults cannot be diagnosed without the assistance of a professional mechanic, who will know how to set about fixing them.
Weather-related problems
Extreme temperatures can be at the source of your engine-starting problems. Both hot and cold spells can cause issues. If it’s too cold you may be vulnerable to:
- Reduced battery output
- Thickened engine oil
- Diesel fuel issues if it’s very cold
In hotter spells, you may experience:
- Overheated electrical components
- Vapour lock in fuel systems
Regular servicing helps to reduce weather-related failures. In cold weather, a jump start may get your car moving again, but if problems persist it may be worth an oil change or garage assistance if it’s particularly nagging.
A car that won’t start isn’t always in need of a major intervention - sometimes you’ll be able to remedy it yourself in a relatively simple way. But repeated failures usually mean the need for a more acute intervention, and at Longmynd Service Station, we’ve seen every issue there is; if you’re having problems with your car not starting, we’re the best option in all of Shropshire.