Why has my car broken down? 10 most common breakdown causes

Car broken down and not sure why? Most breakdowns are caused by common issues like a flat battery, overheating, or problems with your starter motor.

At Marshall Batteries, we’ve seen it all. We’ve helped thousands of Aussie drivers get back on the road with 24/7 roadside battery replacement and breakdown assistance — no membership needed.

Need urgent help now? Holler for a Marshall on 1300 627 742

Below, we break down the top 10 reasons vehicles fail — and what you can do to prevent them, fix them, or get help.

Flat or faulty battery

By far the most common cause of a car breakdown is a flat, damaged or faulty car battery.

The most common causes for a car battery to go flat are:

• You’ve left your headlights or stereo on while parked
• You take lots of short drives
• You’ve left your car unused for a long while
• The battery terminals have corroded
• The battery is old and needs replacing

If you have jumper leads and know how to jump-start your car safely, this can be all you need to get back on the road.

Signs of a faulty battery include:

• You hear a cranking noise but the battery can’t turn the engine over
• The car starts slowly or needs multiple attempts
• A red battery warning light appears on the dashboard

To avoid battery failure, make sure your accessories like headlights and stereo are turned off when you exit the car.

It’s also smart to take your car for a good drive on the motorway each week, and check your car battery’s health occasionally.

If you don’t need to call our roadside service, you can use our battery finder to get a quote from your nearest provider.

Flat tyre/s

Whether you’ve hit a pothole or a kerb, or your tyre has just suffered wear and tear, a burst tyre can be a real kick in the teeth when you have somewhere to be.

If you don’t have a spare or can’t change it yourself, our roadside assistance can help – just call 1300 MARSHALL.

What to look for:

• Visibly deflated tyre
• Unbalanced vehicle — leaning to one side or wheel pulling in a specific direction.

Prevention tips:

• Check your tyre tread depth and pressure regularly
• Avoid potholes, puddles and damaged roads when possible

You’ll usually be able to identify a flat by checking the wheels — but if you’re unsure, our car battery breakdown service team can help inspect it on site.

Alternator faults

The alternator is what converts mechanical energy into electrical energy — in plain terms, it charges your battery while you drive. Your starting battery uses a lot of power to start the car, and the alternator replenishes it.

When it fails:

• Your battery won’t recharge
• A charging warning light may appear
• Electrical systems may flicker or fail

If your alternator fails while driving, your car will likely run flat quickly. Pull over safely and call for assistance 1300 MARSHALL

Misfuelling (or running out of gas)

Fuel problems are another common reason for breakdowns — especially if someone accidentally puts the wrong fuel in the car.

• Putting regular petrol in a car that needs premium may reduce performance
• Putting diesel in a petrol car can cause stalling or failure to start
• Putting petrol in a diesel car can cause significant engine damage if you start the car

If you think you’ve misfuelled, don’t turn on the ignition. Make sure your car is in a safe place, call your local mechanic to arrange an engine flush, and check with your insurance provider.

Check out our full guide on what to do if you’ve put the wrong fuel in your car for more guidance.

To avoid misfuelling your car, look for a label on the inside of your fuel flap and double-check it each time you fill up.

Overheating

Overheating can happen if you run your engine for a long time — especially during a hot Australian summer.

What to look for:

• Steam or smoke from under the bonnet
• Temperature warning light on the dash

If this happens, pull over as soon as it’s safe to do so. Don’t open the radiator while the car is hot — it can cause burns.

Let the engine cool down and then call for roadside assistance ASAP.

Starter motor troubles

The starter motor has to work hard — particularly in modern vehicles with start/stop systems. While it’s built to last, it can eventually fail.

If your battery is fine but the engine still won’t turn over, the starter motor may be the issue.

Tip: Have your car serviced regularly — a mechanic can usually catch early signs of starter motor wear.

Lost, damaged or stolen keys

Misplacing or damaging your car keys isn’t technically a mechanical breakdown — but it’s still one of the leading causes for roadside callouts.

Modern alarms and immobilisers make it impossible to get into your own car without the right key. If:

• Your keys are locked inside the car
• They’re lost
• The key has snapped off in the lock

…you’ll need help from a roadside professional. Holler for a Marshall on 1300 627 742 and we’ll help you out.

Broken clutch cables

Manual transmission drivers will be familiar with clutch cables — they come under pressure every time you shift gears.

Warning signs that your clutch cables are broken:

• Clutch feels different or slack
• You can’t disengage the clutch
• The car won’t go into gear

If you notice that the clutch feels different underfoot, pull over as soon as it’s safe to do so, put the car in neutral, and roll to a safe stop. Then call your local mechanic to arrange a tow.

Diesel Particulate Filter needs cleaning

If you drive a diesel car, the Diesel Particulate Filter (DPF) traps soot and converts it into less harmful gas. Normally, it cleans itself — but if you only make short trips, it can clog up.

DPF issues:

• Warning light on the dashboard
• Loss of power
• Car won’t start in severe cases

You may be able to clear the blockage by driving on the motorway for 30+ minutes. If not, call us on 1300 MARSHALL and our roadside assistance team will help you out.

Ignition wiring or coil faults

Electrical faults in the ignition system can happen in older vehicles or in damp conditions.

Look for:

• Misfiring engine
• Difficulty starting in wet weather
• Trouble idling

If your car isn’t starting and you suspect the ignition to be at fault, call us for roadside assistance.

Broken down? We’re here to help

Holler for a Marshall on 1300 627 742 and we’ll send someone to you ASAP – no membership fees, anywhere in Australia.

Need a new battery today? Use the battery finder and get a quote from your nearest provider.

Car breakdown FAQs