A couple weeks ago, my 2003 RAV4 started missing like crazy and it was diagnosed as having a bad ignition coil (module that fits on top of the spark plug). I replaced it and the truck ran like new with no misfire. Two days later the CEL came on with P0420 and P0430 which are emissions codes. Could this be related to replacing the coil?
PO420/PO430 codes after replacing ignition coil?
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ROCKnRider
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A couple weeks ago, my 2003 RAV4 started missing like crazy and it was diagnosed as having a bad ignition coil (module that fits on top of the spark plug). I replaced it and the truck ran like new with no misfire. Two days later the CEL came on with P0420 and P0430 which are emissions codes. Could this be related to replacing the coil?
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P0420 and P0430 are related to catalyst efficiency in both pipes. It is likely related to running the engine with the spark misfire condition. The unburned gas would accumulate in the cats due to the misfirings, then burn and melt the substrate when proper engine operation was restored. That's the worst case. There is some hope that there is just residual stuff in the converters that will cook off and things will be fine. Go ahead and reset the check engine light and drive it for a couple weeks. If it is still coming back on, take it to a good independent shop that can do converter diagnosis...they need a scan tool at least, and exhaust gas analyzer would be better still.
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I had the codes reset but the CEL came back on after about 100 miles. I hope you're right about the residual burn off and it seems too coincidental to have happened after the coil replacement. Advanced Auto has been great for helping with the the OBD2 check but I don't like to be too much bother so I ordered a scanner and sensor changing tool just in case. I'm not a mechanic but want to know as much as possible before turning it over to the shop. Thanks for the reply.
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I was curious what the outcome was for you, and I am having the exact same issue. Thanks.
The same exact thing just happened o my wife's 2003 RAV4. The #2 coil had to be replaced due to a mis-firing. I also had the spark plugs changed. 1-week later P0420 & P0430 appeared. I reset the engine light and am now waiting to see what happens. Has your light come back on after resetting it? This car only has 84K on it. I must say that I am very disappointed with the repairs that it has required. My wife drives the car very gently, and I am on top of her maintenance. Not too long ago an O2 sensor had to be replaced for $350 by the stealership, and the aluminum tubing for the A/C had to be replaced for $300 because of a hole that appeared when the crappy Toyota mounting bracket wore thru the tubing as the result of a faulty clip design. If have been reading several expensive horror stories about the P0420 & P0430 codes. Mainly due to the stealership replacing components until the light goes out, only to see it come back on a month later. If this turn into a costly repair, bye-bye Toyota for good.
I, too, am having the exact same issue with my 2003 RAV4 with 106,000 miles on it. Had the misfire, took vehicle to mechanic, who replaced one of the coils and all the spark plugs, and changed the oil. Vehicle ran fine after, but started showing P0420 and P0430 several days later.
Went back to my mechanic, who felt it was unlikely that I had actually damaged anything in the limited amount of low-speed driving I did after the misfire (abt 30 miles.) As I live in an area where it's very difficult to drive far enough or fast enough to properly reset things (an island off the Massachusetts coast), he felt that my impending drive to my second home in Florida (abt 1400 miles) might well resolve the problem.The vehicle ran fine on the drive down and got the same gas mileage it always has (abt 24-25 mpg. ) Sadly, it has not resolved the code problem, which will have to be taken care off to pass Mass. inspection when I get back. It also shows the evaporative system as "not ready."
I was wondering if anyone who posted on this issue found resolution, or if anyone has any thoughts on the best way to proceed from here. I'm hoping to avoid a situation resulting in the ongoing random replacement of expensive parts. Thanks in advance.
Jim
Went back to my mechanic, who felt it was unlikely that I had actually damaged anything in the limited amount of low-speed driving I did after the misfire (abt 30 miles.) As I live in an area where it's very difficult to drive far enough or fast enough to properly reset things (an island off the Massachusetts coast), he felt that my impending drive to my second home in Florida (abt 1400 miles) might well resolve the problem.The vehicle ran fine on the drive down and got the same gas mileage it always has (abt 24-25 mpg. ) Sadly, it has not resolved the code problem, which will have to be taken care off to pass Mass. inspection when I get back. It also shows the evaporative system as "not ready."
I was wondering if anyone who posted on this issue found resolution, or if anyone has any thoughts on the best way to proceed from here. I'm hoping to avoid a situation resulting in the ongoing random replacement of expensive parts. Thanks in advance.
Jim
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Similar thing happened to me 5 years ago on a Nissan sentra. Unfortunatelly the only solution was to replace the cat. If you were driving for a bit with cylinder misfiring, unburned fuel goes in the excaust and burns up in the cat destroying it. It cost me $600 just for the cat alone. Sorry to man, you may have a pricey repair.
Thanks, f. I think that, at this point, I'm hoping to find the most accurate route to correct diagnosis, not being sure who's most likely to have the right testing tools to see what's going on. So many of these stories seem to go, "Well, they replaced this, and that didn't work, so they replaced that, ad nauseum......"
Jim
Jim
I know this is an old thread. Wondering if anyone found a solution. I too have had the exact same scenario this year - misfire, replaced coils and plugs, codes started soon after. A lot of these P0420/P0430 threads state things like "cats don't die, they're killed" or "if you didn't do anything to your cat..." It sounds like the misfire very well may have "killed the cat." 
Has anyone gone that route in this scenario and replacing the cat prevented the codes from coming back?
Has anyone gone that route in this scenario and replacing the cat prevented the codes from coming back?
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183 Posts
I can almost guarantee that if you replace the cat your codes will go away. Misfire ruins cats. Aside from something puncturing the cat unburied gasoline is the only thing that can damage it. If you had a misfire and drove the car for a while while missfireing you have to replace it. I know of some people that replaced stock cat with aftermarket, they work, and you can pass emissions in any state but California. Usually you can get those for half of oem price. Search on eBay.
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