CEL coming on intermittently

[CarlW]

Hi

 

Apologies if this has been answered but I picked up my car yesterday, 2004 350z, and after reading about the correct fuel to use I filled up with Tesco Momentum. I'm pretty sure that the car had been run on standard fuel for a while before I picked it up but I figured start as you mean to go on and all.

 

Anyway the CEL has started coming on intermittantly and the error is showing as the catalytic converters aren't functioning properly. If I clear the error the light goes off for a while and then comes on, usually when I get the revs up a little:-) Unfortunately as it's my first weekend with the car that's happening quite often!

 

I'm assuming it's related to changing to 99 octane fuel so I was going to leave it a few weeks to settle in before calling the dealer but I was wondering if anyone else has had this just in case?

 

Any advice would be welcome

 

Thanks

 

Carl

[Ricey]

Any modifications on the car?

 

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[ilogikal1]

Either the cat(s) is/are breading down and need to replaced, the sensor(s) aren't functioning properly or you've got exhaust modifications that the standard sensors don't like (such as decats, for example).

 

If it's only happening when the engine/exhaust is hot and you've got no modifications, it's likely to be the cat(s) are on the way out.

[CarlW]

Only modification is a pop charger that was on it when I got it. I guess it'll be a trip down to the dealer next weekend then:-(

[evest]

What code are you getting?

[CarlW]

Hi, the first time I think it was 0420 and 0421 showing erros on both cats, the second was just 0420 so showing an error on one of them.

 

Thanks

 

Carl

[evest]

What's the mileage. Just thinking it might be dirty O2 sensors causing an error code to appear. I had error code so cleaned the O2 sensors and have had nothing since.

[CarlW]

The mileage is just over 91K, I took the car for some extended test drives before buying it and there was no problem. The only thing I've done between then and now is filling up with SUL and getting it valeted.

[evest]

OK - just seems too much of a coincidence that both cats would go like this just after you got the car and changed fuel. Perfect opportunity to upgrade to some HFC's...?

[CarlW]

Lol, funny enough I was thinking just that although I'd have to put my new stereo on hold for a while. Mind you with the way the car sounds who needs music:-)

[Zeezeebaba]

This is a fairly common Z issue especially post cat sensors. Mine wound me up so much I bought HFCs and an Uprev map to blank out the rear sensors for good.

[CarlW]

The way these suggestions are going I'm going to end up in the poor house

[B16]

Been thinking about some HFC's too as I've had two CEL's in the past month or so, both P1147 which I think is 2nd o2 sensor on bank 2... Cleared the code with a code reader and then pedal dance although the pedal dance took me about 10 attempts to get right 😩

If the CEL is annoying you I definitely recommend the pedal dance to clear it, I'm sure you'll find a thread with instructions on here!

 

Also both times the light came on, it was a cold start on a fairly cold evening (think about 8 degrees) so I don't think it likes the cold. I can't wait to see what happens when it gets really cold 🙄

 

 

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Edited October 24, 2016 by B16

[CarlW]

Had a word with the garage I got it from today and they agreed to replace both cats so HFC's will have to wait a little while. Mind you now the seed has been sown I'm thinking HFC's, Invidia Gemini Exhaust and UpRev will be on the cards next Spring!

 

Just have to keep it quiet from the wife