[adc]

I hooked up a code reader and got this: P1420. After searching this site, I found out it means:
Secondary Air Valve Control Circuit Electrical

Last evening heading home, WOT in 2nd gear the car stumbled as if hitting the rev limiter, then continued running very rough. Like not all cylinders were firing. After 10sec the half-engine yellow light came on.

A restart fixed the rough running and the engine light went off.

But today I tried again WOT in 1st gear and got the same problem. Only this time the yellow SES became illuminated.


Anybody have any idea what it relates to, or what I should check?

[adc]

Can this be caused by a loose gas cap?

Taking my best guess, I started checked for vacuum leaks in the engine compartment and found none (air filter, boost solenoids, etc.). Then just to be sure, I removed and replaced the gas cap making sure it's tight.

I tried my WOT test again and the car ran fine. I then reset the OBD code and will try again tonight on my way home.

It would be cool if we can associate any of these murky codes with a small checklist that anybody can go through...

[adc]

Not the gas cap, definitely. Unfortunately.

I have to stop answering my own questions...

Next step, the dealer.

[kptaylor]

http://www.e90post.com/forums/showth...ighlight=P1420

Cat sensor issue.

[adc]

Originally Posted by kptaylor

http://www.e90post.com/forums/showth...ighlight=P1420

Cat sensor issue.

I did search! Came up with the above link, but also this:
http://www.e90post.com/forums/showth...ighlight=p1420
And this:
http://www.e90post.com/forums/showth...ighlight=p1420

I also googled the code and for BMW it always came back as the secondary air valve thingie.


Thanks for the pointer though, I was so convinced the link you mentioned points to the same 1420 code, I didn't actually check the text. Perhaps I can take it in to the dealer right now...

Once again, thanks!