02 Honda Civic won't start in cold

I bought this car last summer and it has run great until last week. My car sits outside, and on a night when the temp dipped to 12 below, it wouldn’t start the next morning. Checked spark plugs–good. Replaced original battery. Put in HEET. Full tank of gas. After 3 days, managed to coax it to start and then it ran ok for 3 days, coughing a little every time I started it. But then it wouldn’t start again this morning, even though it’s not as cold as it was last week. Turns over fine, really wants to start, but won’t fire up.

How did you check the plugs? What about other ignition components like wires, coil(s), distributor (if any - I don’t know the ignition system on this car). The quickie way to look for problems there is to pull the plugs and check for a good strong blue spark.

The quickie check for a fuel problem is to spray starter fluid or something similar into the intake - if it fires at least briefly then you have a fuel problem. How old is the fuel filter? Check fuel pressure against specs (fuel pressure gauges are not that expensive). Check the fuel injectors for operation. You can get a “noid” light at an AP store to check for power pulse to the injectors.

Have you checked or replaced the air filter?

The cold weather may have just been coincidental to the engine not starting.
At 60,000+ miles, the original, dirty, fuel filter is a prime suspect for a no-start and reduced performance/stalls. Unfortunately, for you, it seems that you Civic does NOT have an external fuel filter. It’s in the fuel tank. So, actual checks with a fuel pressure tester is needed to check fuel pressure with engine OFF, at idle, AND then, with the engine under load. You can load an engine by placing the fuel pressure test gauge where you can see it and drive the car with your foot on the brake pedal. You need to load the engine for about three minuets.

If it’s anything like my 99 Civic that is well maintained as far as plugs, fuel filter, oil changes - everything in the manual - at times when cold and esp. if low on fuel, it will not start unless I turn the key to On (not Start) then Off and repeat this a few times, waiting for the fuel pump to run its couple of seconds each time it’s at On. That seems to bring up fuel pressure enough to allow the car to start. Once it starts, it’s fine.

My 2005 Civic EX does the exact same thing. Already replaced the plugs coil packs and main ECU relays. Wondering if anyone knows exactly what it is? Im going after the fuel pump next.

@Gordan_Voshell

When it won’t start, try giving it some fuel by pressing on the gas pedal. I know you aren’t supposed to do that with a fuel injected engine, but if it starts when you do that, I suspect an issue with the idle air control valve.

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I did try that and it doesnt help…