Car Won't Start in Cold Weather? A Colorado Guide
The first hard freeze along the Front Range always brings a wave of dead batteries. Here is how to tell what is wrong from the sounds your car makes, what to try, and how to stop it happening again.
Why cold weather kills car starts
Cold slows the chemical reaction inside a battery, so it delivers less power right when the engine needs more: cold oil is thick and the starter has to work harder. A battery can lose a large share of its starting power as the temperature drops toward zero, according to commonly cited battery-industry figures. A battery that is three or more years old, or that is already a little weak, is the one that quits first.
What the sound tells you
| What you hear | Most likely cause | Try this |
|---|---|---|
| Rapid clicking, dim dash lights | Weak or dead battery | Jump start, or a jump pack. See how to jump-start a car. |
| Slow, labored cranking (rur-rur-rur) | Weak battery, thick oil, or loose terminals | Turn off accessories, wait a minute, try again for no more than 10 seconds. Check that the battery cables are tight. |
| One loud click, then nothing | Starter or a poor connection | Check terminals for corrosion. Tapping the starter is a last resort. Call for help if it persists. |
| Engine cranks normally but will not start | Fuel, spark or air problem. In very cold weather, a diesel's fuel can gel. | Wait and try again. If you have a diesel, use cold-weather fuel additive. Otherwise a mechanic is needed. |
| Nothing at all, no lights | Fully dead battery or a loose cable | Check the terminals, then jump or charge. |
What to try, in order
- Turn everything off: heater, defrost, lights, radio. Put the gear selector in Park or Neutral.
- Wait 30 to 60 seconds between tries, and do not crank for more than about 10 seconds at a time. Long cranking can overheat the starter and drain the battery further.
- Check the battery terminals. Loose or crusty terminals can look like a dead battery.
- Get a jump from another car or a portable jump pack.
- Let it run, then drive to recharge. Our post on how long to run the car after a jump has the details.
How to prevent a no-start in Colorado
- Test the battery in the fall. Many parts stores will do it for free. Replace it if it is weak, especially after three to five years.
- Park in a garage or on the sunny side when possible.
- Keep terminals clean and tight.
- Take longer drives sometimes. Lots of short trips do not recharge the battery fully.
- Use a battery tender if the car sits for days.
- Keep a charged jump pack or good cables in the trunk, and a blanket and gloves in case you wait.
- Block heaters help in extremely cold places such as the mountains, if your car has one.
When to stop trying and call
If the car will not start after a jump, you smell fuel, or you have been cranking repeatedly, stop. Repeated tries can flood the engine or run the battery flat. A roadside helper can bring a jump pack and also check whether it is the battery or something else, and tell you honestly if you need a tow.
Want roadside help on your side before you need it?
ShoulderCrew is a membership for roadside help in the Denver area: jump starts, lockouts, flat changes and fuel delivery from local helpers, from $5.49/mo or $39/yr. It is help on the spot, not reimbursement, and towing is not included. We are launching in Denver first, and helper booking turns on as local helpers are verified, so join now to be first in line.
See membership plansSign up freeCommon questions
Why won't my car start when it's cold?
Cold weather slows the chemical reaction in the battery, so it delivers less power, while cold oil makes the engine harder to turn. A weak or older battery is the most common reason a car fails to start on a cold morning.
How many times should I try to start a car in the cold?
Try for about 10 seconds at a time, with 30 to 60 seconds in between. Repeated long cranking can drain the battery and overheat the starter.
Should I jump-start or replace a battery that dies in the cold?
A jump will get you going, but if the battery is more than three or four years old or dies again, have it tested and replaced if it fails.