ah! the infamous P0420 code! what now

Jun 4, 2009 | 11:55 AM

Xander

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ah! the infamous P0420 code! what now

So the CEL came on today on my way to work. So at lunch I run by advanced auto and have the guy plug it in..P0420...he reset it and it is off now. but Im sure it will be back

I have called the dealer and left a message...

anything I should know to say to them? I think the cat is bad..a few months back my coils failed and i was on the highway trying to get the horrible running car home and it started filling with smoke from under the ebrake area...I assume I hurt the cat with unburnt fuel..

anyways any insight would be great! I dont want to pay them any $!!

car is 04 w 57k miles

Jun 4, 2009 | 01:11 PM

Atilla

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From: Caca Cali

replace under warranty or upgrade to a hi-flo cat.

Jun 4, 2009 | 01:24 PM

Xander

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Quote:

Originally Posted by Charles R. Hill

Although you should be getting a new catpipe under warranty (according to federal regs) you may also want to push the idea to the dealer of looking into the coils, wires, and plugs because faulty coils probably started a while back. When this happens, the cat can sometimes be the first to evidence itself.

i actually just replaced these about 2 months ago...

Jun 4, 2009 | 03:47 PM

Xander

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Quote:

Originally Posted by Charles R. Hill

Ah. The cat was already on the way out because of the bad coils then.

yea thats what im thinkin....

so heres the update..i call kerry mazda in florence and they want to charge me $85 to hook it up and see if that is in fact whats wrong with it..if it is the cat...i wont have to pay..if its somthing else...im stuck paying that amount

sound legit?

Jun 5, 2009 | 07:36 AM

Xander

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Quote:

Originally Posted by Charles R. Hill

Since you have the 420 code I wouldn't worry about it. They'll find it to not be your fault and it should be covered under warranty. Just keep in mind that properly operating emissions systems are mandated by Federal regs.

ok so now the CEL is gone....what now? should I still take it in? if it was bad one day it didnt fix itself but Im afraid they will tell me that since its not throwing the code they cant replace it..i have been hoping since yesterday that it would come back on..

Jun 8, 2009 | 02:54 PM

NotAPreppie

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From: 2017 Miata RF Launch Edition

Some CEL's will clear themselves if the error condition go away for enough start/stop cycles. Since cats don't generally magically fix themselves, yours is probably just marginal and it's hovering at the threshold where the ECU decides to throw a code.

The error code will likely still be stored in the ECU and their diagnostic scanner should be able to read it. I'd take it in and politely request that they make this intermittent issue disappear.