CEL came on and now it’s off… P0420 code

Seeking Help Forum
1

Got a CEL for a P0420 code, but it went off on its own. Anyone else dealt with this? Wondering if I should still bring it to the dealer while under emissions warranty, or just wait and see if it comes back.

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We’ve had a P0430 code (bank 2 side) for about 10,000 miles now and it’s still running fine. We tried replacing the O2 sensors and did a couple of Italian tune-ups, but it didn’t change anything. There’s no power loss or hit to fuel economy. Since we don’t have emissions testing, it’s low priority until we can budget for new cats.

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@Mason
We have emissions testing here, so if it comes back, I’ll probably have to take it in. Hoping they’ll cover it under warranty.

4

I have the same code on my 2016. It pops up every now and then, but I haven’t noticed any issues and still pass my state’s smog test. I joke that it’s my ‘permanent’ CEL at this point.

5

EcoBoost engines really don’t like short trips or easy driving. If you don’t fully warm up the engine every time, the cats can clog up quickly with carbon. This code can be triggered even if the catalytic converter is just a bit below full efficiency (like 94% instead of 100%). I used the ‘Italian tune-up’ on my 2015 Navigator: filled it with premium gas, warmed it up fully, then did some highway driving around 3-4k RPMs and a few hard pulls. So far, the code hasn’t come back. My wife’s commute is only 2 miles, so that could be why it clogged up.

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@Zander
Thanks! My wife has a very short, slow commute to work, too. Think it’s worth taking it to the dealer while it’s under emissions warranty?

7

Jessie said:
@Zander
Thanks! My wife has a very short, slow commute to work, too. Think it’s worth taking it to the dealer while it’s under emissions warranty?

Definitely, they’ll probably just replace the cats, which is good. Then try to take it out on weekends for a long drive with some acceleration to keep it clear.

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Alston said:
30K miles & CEL w/P0420 & P0430 | Ford Expedition Forum

Thanks! I’m just waiting for the CEL to come back on so I can take it to the dealer. If I bring it in now, they’ll probably say there’s nothing wrong. Appreciate the link. Glad yours is running better.