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P0492 Secondary Air Injection error


29 Jul 2021
Hi all,

I had a 160 mile round trip today, so good to go for a decent run. They're a decent car alright that really can do the school run, the Nurbergring and everything in between!

Anyway, a couple of times coming to a stand still, with the everything fully warmed up, the idle would dip whilst sitting... Just a bit, and didn't seem like it was going to cut out.

So I check the error codes, and there was P0492 Secondary Air Injection error - reading around this is just to warm up the cats during the start up? So whilst needs to be sorted, wouldn't be related?

And I assume it's not a big problem in and of itself? It was only one bank, but looks like it's not an easy DIY to get to the bits.

Any advise appreciated.
Secondary air is as you have said .. its to fast warm up the cats from cold .. it lasts about 30 seconds and switches off .

Your code indicates that bank is probably blocked causing it to be ineffective .

This Will Not cause any running or idle issues .

At best i would suggest a clean of the throttle housing .. these do get gummed up and are not attended to on any service .

Other than that then drive until there is an actual issue or its ok .
Thank you for the info!

I've cleared the fault just to see if it's intermittent.

When you say the the throttle housing, it's the throttle body right? So should be easy to get to? And just use some carb cleaner to get the dried oil out?
Remove the air filter box and you can get at the throttle flap .. clean rag will do the job , just lift the flap up and wipe the area .

No ignition keys in the lock obviously :)

G2 pictured but it shows the throttle which is what's needed to be cleaned .


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That's great, makes sense! I'll do that and keep an eye on the fault codes.


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