I was driving on a 7 degree morning and within a mile from home going 10mph my check engine light started blinking and I could no longer accelerate above 10-15 mph. I made it home and checked the code P0304 (MISFIRE) and a catalytic converter code from a year ago.
Later that day (it was a bit warmer) I started the car and the engine light was not blinking and it drove fine around the neighborhood at 25 mph.
What could cause this? Roughly how much is it to fix?
Thanks so much in advance
A P304 missfire means your number 4 cylinder has a missfire issue bad enough to force the car into limp home mode. Likely a failing ignion coil or spark plug or both. If the car has lots of miles on it, you should replace all the spark plugs and the #4 ignition coil.
I can’t guess what it will cost since I don’t know where you live - prices vary a lot between Kansas and California.
Please explain this a little better…
Is it a history code?
Did you ever repair the cat? if so, was it never cleared?
Ditto to what Mustangman said, replace the spark plugs with the correct OEM (not just an equivalent) spark plugs and a quality ignition coil, I would stay away from auto zone…
Of course check the plug connection for the coil to make sure it is properly connected…
Thanks for this advice. The catalytic converter code came on for 3 days (engine light) and went away for a year. Then this issue happened and the code was still there when I checked it.
However after driving around the block about 2 miles, the p0304 code is now gone. I’m not going to pretend my car is fine but why would it go away like that?
Was it an error or something because it was extremely cold that morning (7 degrees) or it the issue still there?
It’s definitely confusing
With plugs and coils, you’re talking about electrical things which can just get squirrelly as they start to fail. And temperature can have a lot to do with that.
On the subject of replacing the #4 coil, my own preference is to first swap two coils (assuming these are independent coils on plug) to see if the misfire goes with the coil. Certainly do the plugs though…
Thanks so much man!
I’ll do that
Concur w/post above (@cigroller ), likely a bad electrical connection due to parts & wires changing dimensions in cold weather. Could also be the very thin high voltage generating wire inside the coil has a break somewhere. Diy’er me would probably inspect the coil and spark plug, and otherwise just disconnect and reconnect a couple of times, then monitor the situation. But if you absolutely need a reliable ride, best to not use my “hope and prayer” method. . At a minimum, suggest to replace all four spark plugs and the number 4 ignition coil.
Then monitor the error codes carefully. Sometimes w/a misfire the computer will accuse the wrong coil.
The reason I suggested starting with just swapping coils first, is why replace a coil if you don’t know it’s bad? (E.g. why spend the $$ even though it appears that these aren’t all that expensive).
If they were hard to do then I wouldn’t even say to replace #4. I’d say to replace them all. They’re all likely the same age. Sure, one can just go for whatever reason, but if one goes, the others are often not far behind. So, if it was a lot of labor there’s be no point in just doing one.
But these are just typical “right-on-top” 4-banger coils. You can swap them around in something like 10 mins. Then if there’s another misfire and it’s gone with the coil, that’s fairly conclusive evidence of a bad coil.
@Ashabea21_192138 , if you do end up replacing any coils, I always go with OEM. That doesn’t mean you need to buy from a dealer. Just look it up - they’re probably made by Denso, or maybe NGK. So you can buy them on the “aftermarket” but non-OEM coils can be an issue with many makes/models.
For looking at that I’d browse around on CRV owner discussion boards.