Car Won't Start? A Mechanic's Checklist by Sound

What does your car do when you turn the key?

The sound tells you most of the story. "It won't start" can mean five different things, and they have different causes. Turn the key or press the button once, and pay attention to the noise and the dash lights.

If you can, take a 10-second video with your phone. A mechanic can learn a lot from hearing it, and it's more accurate than trying to describe it later.

• Nothing at all, and the dash stays dark: no power reaching the car. Dead battery, a loose or corroded terminal, or a main connection problem.
• One click, then nothing, with dash lights on: power is there but the starter isn't turning. Starter, starter relay or a bad connection at the starter.
• Rapid clicking, like a tick-tick-tick: the battery has enough to work the starter switch but not enough to spin the engine. Usually a low battery.
• Slow, dragging crank (rrr... rrr...): weak battery, very cold oil, or both. Common on the first properly cold morning of the year.
• Normal-speed crank but it never fires: the starting system is fine. Look at fuel, spark, the immobilizer or a sensor.
• Starts, then dies after a second or two: often the anti-theft system not recognizing the key, or a fuel delivery problem.

Click, no click, or cranks but won't start

Rapid clicking is the most common winter no-start we hear about, and it's usually a battery that's low or tired. A boost will often get you going. That doesn't mean the battery's the whole story, though. If it went flat because the alternator isn't charging, or because something is draining it overnight, a new battery will be dead again by Friday.

A single clean click with bright dash lights is different. The battery is probably fine, and the starter or its wiring isn't doing its job. People sometimes tap the starter with something to get one more start out of it. Sometimes it works. It's a sign the starter's on its way out, not a fix.

If it cranks at normal speed and doesn't catch, stop blaming the battery. Something isn't getting fuel or spark, or the car's anti-theft system doesn't recognize the key. Look for a flashing key or lock symbol on the dash. That's worth a photo.

Don't keep cranking it. Long cranking runs the battery flat and heats the starter, which isn't built to spin for a minute straight. You'll turn a dead battery into a dead battery and a cooked starter. Give it a few short tries with a pause between, then stop.

Why it always happens on the coldest morning

Cold makes everything harder at once. The engine oil thickens, so the engine takes more effort to turn, and a battery has less to give when it's cold. CAA puts it simply: a battery works harder in cold temperatures, so a weak one is a liability. A battery that was fine in October can give up on the first -25 °C morning in January, especially in Shediac with the wind coming straight off the Northumberland Strait.

Age matters too. CAA notes that a battery between three and five years old could fail. If yours is in that window and you've noticed slower starts, get it tested before the deep cold, not after.

Short trips make it worse. Ten minutes from Dieppe to downtown Moncton with the heater, seat warmers and rear defrost all running doesn't put much back into the battery. Do that all week and the battery goes into Saturday morning half empty.

• Plug in the block heater when it gets below about -15 °C. CAA suggests it below that temperature.
• Use a timer. Natural Resources Canada says two hours before you leave is more than enough. You don't need it plugged in all night.
• Keep the tank at least half full in winter. CAA says it cuts condensation that can freeze and block fuel.
• Turn off the heater fan, headlights and defrost before you try to start, so all the battery's power goes to the starter.

Push-button start? Check the key fob first

If the dash says "key not detected" or nothing happens when you press the button, the fob battery may be the problem, not the car. Fob batteries are small and die quietly, and cold doesn't help.

Most push-button cars have a backup. On many models you hold the fob right against the start button, foot hard on the brake, and press. Mazda's manual, for example, has you press the brake, touch the back of the key to the start button while the indicator flashes, then press the button. The exact method differs by make, so check your owner's manual. Once you're going, replace the fob battery. It's a coin cell and usually a five-minute job.

For keyed cars, two quick checks. Make sure the shifter is fully in Park; nudge it and try again. If the key won't turn, the steering lock may be on, so wiggle the wheel while you turn the key.

When to stop and call someone

Stop trying and get help if you smell raw fuel, see smoke, smell hot plastic or wiring, or hear grinding or heavy knocking when you try to start. Same if the car shut off on the road with an oil pressure or overheating warning just before. Cranking a car in that state can turn a repair into an engine.

If you boost it and it starts, let it run, but don't assume it's sorted. A car that needed a boost needs the battery and charging system tested. Otherwise you'll be doing this again in the parking lot at Champlain Place on the coldest Saturday of the year.

What to tell the mechanic

The right details cut diagnostic time and help us bring the right parts the first time. You don't need to guess the part. Tell us what happened and when.

If you're in Dieppe, Moncton, Riverview or Shediac, send the vehicle, the problem and your postal code, or call or text (506) 871-0669. We'll call back, go over what you're hearing and confirm the price before anyone drives out. Battery, starter and charging problems are often fixed right in the driveway. If it turns out to be something that needs a hoist, we'll take it into a shop and handle the repair from there.