Jeep Wrangler: Won’t Start When Cold → Diagnosis

Wrangler Won't Start When Cold

Extreme weather can be very difficult on your Jeep Wrangler.  If there is an issue it often make itself known when conditions are at their worst.  When it’s extremely hot. it’s the cooling system that is put to the test.  In the winter, the vehicle won’t start when it is cold.  

There are a few different reasons that can cause this, but it’s usually your Wrangler’s battery that can’t handle turning the engine when it’s cold.

It very well could be the cold weather that is keeping your Wrangler from starting.  But, you don’t want to rule out that it’s just not starting, and it happens to be cold.  Check out Jeep Wrangler Not Starting if this seems it may be an issue for you.


Jeep Wrangler:  Won’t Start Cold – Causes

Hard Start Cold Jeep Wrangler

1. Battery Capacity Diminished

Far and away the number one reason that your Wrangler won’t start in the cold is the battery.  A battery has two different ratings, cranking amps and cold cranking amps.  Cold cranking amps are the batteries ability to start turn the engine over when it is cold.

Battery capacity diminishes with time and use.  So it may have enough cranking capacity to start the vehicle when it is warm, but when it’s cold, it just isn’t enough to turn the engine over anymore.


2. Wrong Battery

If you happened to have purchased a battery when the weather was warm, and now less than a year later it’s not starting your Wrangler, you may have purchased a battery that doesn’t have the cold cranking capacity that your car needs to get started.  

This often happens when you have a six cylinder model, and you get the battery for a four cylinder.  They don’t have quite enough capacity to turn over a heavier motor when it’s really cold.

How to Start Jeep Wrangler in Cold Weather
The battery is the number one reason why your Wrangler won’t start in cold weather


3. Wrong Oil Viscosity

If you put a heavier oil in during the warmer months, it’s not as likely to keep your Wrangler from starting.  But, in the winter, it’ll make itself known.  The heavier molecules in the thicker oil can keep the engine from turning over fast enough to start.  For instance, maybe you bought 10W-30 when the manufacturer called for 5W-30.


4. Water in Fuel Line

Condensation can build up in the gas tank as temperatures change.  If the condensation finds its way into your Jeep Wrangler’s fuel line, it can freeze and leave the engine unable to turn over.  If the engine is cranking fast, as though the battery is fine, this is a definite possibility.


How to Start Your Wrangler in the Cold

Here are some tried and true ways to start your car in the cold.  They are presented in a way that would help you troubleshoot a car that you may be sitting in right now in the order that makes most sense for getting you moving right away.  Most of the time it’s going to be a battery related issue, so that’s what we are focusing on.


1. Turn on All of the Accessories and Lights

This may sound counterintuitive when the battery isn’t working very well to begin with.  What you are trying to do is give your Wrangler’s battery a little time to “wake up”.  Once you do that go ahead and turn the key to the “on” position, but don’t start the car for at least 10 seconds.  This gives the fuel pump plenty of time to prime the injectors.  Now, go ahead and try turning the engine over and see if it’ll start.


2. Warm the Battery

If you are at home, and aren’t in a rush, you can unhook the battery and take it inside.  This will allow it to heat up to a temperature that’ll get the electrons in it moving.  Leave it inside for a few hours.  This can really help it crank the car over.  Be careful handling the battery.


3. Jump Start

Jumping the Wrangler will get it moving around again in no time.  Jump starting utilizes the power from another vehicles battery and alternator to charge your battery and help the vehicle start right there on the spot.  You don’t want to let the engine cool all the way down, as it probably won’t start on its own until it’s warm outside.


4. Replace the Battery

You can take the battery into the local parts store to have it tested.  That would be prudent before outright replacing it.  You should look up the cold cranking requirement for your particular Wrangler’s engine and model year.

You want to get a battery that can handle at a minimum what the manufacturer recommends.  Cold cranking amps are a standard.  A battery must crank for 30 seconds at 0° with a minimum voltage in order to meet it.


Conclusion:  Wrangler Won’t Start in the Cold

If any of the battery related issues ended up being the reason why your Jeep Wrangler wouldn’t start, it’s time to replace the battery.  If it warms back up outside, you may get a few good starts out of it, but its days are numbered.