10 Reasons Your Car Won't Start (and What to Do About it)
In the blistering summer heat or the dead of winter, it’s frustrating when your car won’t start. Car problems can disrupt your schedule and the unexpected expense can burn a hole in your wallet. If your car won’t start, the problem could be relatively simple or quite complex.
Unfortunately, there are plenty of things it can be, but for DIYers and handy people, it may be possible to diagnose and repair your car problems and get it running again.
If you do decide to tackle the job yourself, make sure to follow the instructions of your owner’s manual closely and adhere to all necessary safety precautions.
Here are 10 reasons your car won’t start and what to do about it.
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1. Dead starter motor
The engine starter motor engages with the flywheel at the rear of the engine. It’s a 12-volt electric motor and because it’s exposed to the elements, it can become corroded. It can also just fail after thousands of engine starts.
What to do about it
The starter motor can usually be replaced and you’ll be up and running again. The parts range depending on your make and model with an average price being around $350. It may take less than an hour on some cars while others will require more serious time commitment and knowledge.
DIY Difficulty Level: 3/5
2. Spark plug issues
Spark plugs ignite the air-fuel mixture that’s injected into the cylinders. For spark plugs that don’t spark dependably, it will cause an engine misfire that robs you of performance. Cracked porcelain insulators and worn electrodes are the common issue. If more than one spark plug fails, your engine may not start.
What to do about it
A diagnostic scan can help determine which cylinders are misfiring. The faulty spark plugs must be replaced, but it’s best to replace all of them at the same time. It’s a minor repair for most cars and is one of the most cost-effective as well.
DIY Difficulty Level: 1.5/5
3. Timing belt skipped or broke
The timing belt connects the crankshaft with the camshaft (or camshafts, depending on your engine). It syncs the timing for all the engine’s cycles. As a rubber belt, it’s prone to wear and it can fail if it’s saturated with oil. It can stretch and skip a cog or two, or the belt can break. For some engines, timing belt issues can be catastrophic.
What to do about it
Remove the front engine cover and inspect if the timing belt has broken or skipped teeth. For a broken timing belt, inspect the pistons and valves with a borescope to see if they’ve been bent or impacted. The timing belt needs to be installed in exactly the correct position, but major top end work might also be required.
DIY Difficulty Level: 5/5
4. No spark from ignition coil
Ignition coils amplify electrical pulses and deliver the charge to spark plugs to light the air-fuel mixture in the cylinder. Your engine may not start if an ignition coil isn’t firing up a spark plug. It could be a faulty coil, a poor connection to the ignition coil, or a control module that’s causing the problem.
What to do about it
Confirming the problem is usually as easy as swapping ignition coils. With an ohmmeter, you can also check that the wiring to the ignition coil is intact. Installing a new ignition coil is one of the easier tasks you may need to perform, but coils can be several hundred dollars.
DIY Difficulty Level: 2/5
5. Restricted fuel filter
Constant fuel pressure is necessary for the engine to run. A routine maintenance item, the fuel filter, may collect debris that’s in the fuel tank and become plugged, preventing fuel pressure from building up.
What to do about it
The fuel filter takes minutes to change on most vehicles if it’s a serviceable component. If it’s in the fuel tank on the fuel pump module, it could take hours to replace.
DIY Difficulty Level: 2.5/5
6. Fuel pump shorted
If the fuel filter is good but there’s no fuel pressure, it could be the fuel pump itself. As an electrical component, it’s possible for the pump to fail without warning. Again, without fuel pressure, the engine won’t start.
What to do about it
Most fuel pumps are in the tank nowadays. Check the fuse, test for fuel pressure at the engine, check electrical continuity at the tank, and replace the fuel pump if necessary.
DIY Difficulty Level: 3.5/5
7. Dead battery
A car battery’s usable life is usually three to six years, then it begins to have trouble holding a charge. But a dead battery could also be a charging system problem like a faulty alternator or corroded wiring.
What to do about it
Boost the battery, then test if the alternator is charging at more than 12 volts. If it isn’t, replace the alternator. Charge the battery fully and replace if it can’t hold enough charge to start your car.
DIY Difficulty level: 1.5/5
Read more: Ultimate Car Battery Guide: How to Charge, Maintain, Replace, and more
8. Mass air flow sensor fault
The mass air flow sensor (MAF sensor) measures the air entering the engine. If it doesn’t detect the correct amount of air, the air-fuel mixture will be incorrect. It could be either a connector or the sensor itself at fault.
What to do about it
Too much fuel and not enough air is what’s known as running “rich”. Too much air and not enough fuel is known as running “lean”.Perform a diagnostic scan to check for codes related to running lean or rich. You should also check for a MAF circuit issue. Check that the connector is seated properly and replace the sensor if required.
DIY Difficulty level: 2.5/5
9. Ignition cylinder stuck
If you can’t turn the key in the ignition, your engine won’t start – obviously. It can be due to the ignition cylinder or the steering column itself binding.
What to do about it
The ignition cylinder will need to be removed to see if it can turn on its own. If not, replace the ignition cylinder and have the new cylinder and keys programmed to the car’s security system. If the ignition cylinder isn’t the issue, the steering column needs to be swapped out which will also likely require a new ignition cylinder and/or switch. It’s a lengthy job that requires specialized dealer tools, and a steering column replacement can be quite costly.
DIY Difficulty Level: 4/5
10. Faulty security system
If your car won’t start mysteriously or starts and immediately stalls, it could be the factory immobilizer or security system that’s failed. While uncommon, it can happen.
What to do about it
A flashing key icon or security warning on the dash can help you start looking in the right direction. A diagnostic scan will need to be performed to check for security codes. It could be due to a faulty module, broken wiring, ignition switch, or other causes. Fixing security issues is almost impossible to do without high-tech dealer equipment in your garage.
DIY Difficulty level: 4.5/5
Time for an upgrade?
Some problems are simple enough, such as changing the battery or replacing the fuel filter. But for other concerns, especially for older cars, you may want to consider what your car is worth and if it’s better to get something newer.
Rather than spend all your time fixing your car, explore your options. Maybe selling or trading in your car would afford you more time and less hassle than constantly working under the hood.
Canada Drives lets you shop certified used cars 100% online. Our vehicles are meticulously reconditioned, warrantied, and include free CARFAX and 150-point inspections.
