Flashing cruise control light and P0303 code

[ArtD]

First off, Hi everybody! I've got a 2005 STI with 62,000 miles. We bought it new, its my wife's daily driver, and my hot rod when needed Its bone stock, no mods at all. The other day all of a sudden the cruise control light started flashing and the "check engine light" came on. She was driving, and said that it seemed that both things happened at the same time. I have a basic scanner, I pulled the code, its P0303- "#3 cyl misfiring". I should mention that it most certainly needs at least plugs, as the engine is idling a bit rough at times and they are the originals. But there is no miss at all at any speed, just a very slight stumble occasionally at idle. The cruise control was off, we don't use it anyway. I made sure that it was off, but the check engine and the flashing cruise control light were still there. I re-set the ECU,(disconnected the - cable, waited 5 min), the lights both went out. and they stayed off for a few days, and then they both came back on. Any ideas, guys????

[SD_GR]

Since the car is stock, take the code at face value and look into #3 ignition. I'd first see if you can get the problem to "switch" cylinders by swapping the coil for 3 with another. You need plugs anyway, so replace them and take a close look at them all, see what they've got on them as far as deposits go etc. When you're looking at the coil "cover" bit, check for cracks or weird discolourations.

With any luck it's just a loose connection and/or an aging plug. (Sometimes if the coil pack is lose and it's dark in the motor bay you can see faint arcing -- I mention it as a curiosity, not because I'm suggesting anyone put their face as close as possible etc -- be careful, there are real potential differences in the ignition).

None of this is fun to do but grin and bear it and hopefully it'll be a simple "aha!" fix.

[ArtD]

Since the car is stock, take the code at face value and look into #3 ignition. I'd first see if you can get the problem to "switch" cylinders by swapping the coil for 3 with another. You need plugs anyway, so replace them and take a close look at them all, see what they've got on them as far as deposits go etc. When you're looking at the coil "cover" bit, check for cracks or weird discolourations.

With any luck it's just a loose connection and/or an aging plug. (Sometimes if the coil pack is lose and it's dark in the motor bay you can see faint arcing -- I mention it as a curiosity, not because I'm suggesting anyone put their face as close as possible etc -- be careful, there are real potential differences in the ignition).

None of this is fun to do but grin and bear it and hopefully it'll be a simple "aha!" fix.

Thanks, the plugs were on the schedule at the next oil change, I can just move that up a bit and add to it. Let me ask, how does the flashing cruise control light figure into this? Does the check engine light trigger the cruise control light???? Why would they both come on at the same time?

[SD_GR]

I think what happens is the car will not allow cruise control to operate when the CEL is on, so the cruise control light flashes to tell you it's not working.

[subytech209]

dont worry about the flashing cruse light that is a default, when the check engine light is set the cruse control is disabled. but ya first on ur sti u shoulg change the spark plugs at 60,000 at least so do that first and if the check engine light comes back on then take the #1 and the #3 coil packs and switch them and clear the pcm, when the check engine light comes back on check the code if the code is the same then most likely u have inturnal damage wheater it be a valve or piston, but if the code is p0301 then its the coil pack, just replace it and u should be good. let me know.

[ArtD]

Just wanted to let you guys know that it was, in fact a bad coil. As an fyi, the computer seemed to "remember" it, because it really threw me, I reset the ECU, but, the next day the light came back on yet again, and then, about a day later, went off and has stayed off. Good thing, because I was going to say f**k it and just leave it, Subie was running fine