P0491 and P0492 Codes
 

Well, I have the infamous P0491 and P0492 codes. I've already replaced the valve (the one that's on the passenger front side of the engine). The old one was pretty toast. The light was off for about a week. Now, it's back on. I can hear the secondary air pump come on when I start it up in the mornings (faint sound). Could it be the air pump? All the hoses appear to be in good shape.

Any help would be greatly appreciated.

Dan

insufficient flow in bank 1 and 2. if you need to change two parts and you only changed one then i suggest you change the other.

Picked up the air pump this afternoon. $287 with tax...ouch!!! I'll tackle it this weekend.

Dan

Well, I didn't tackle it that weekend, so I tackled it last night after school. The light was off for a couple of weeks until yesterday. Looks like it was the pump. You could hear the motor in the old pump come on and off. With the new one, you cannot hear anything. Hopefully, this will solve my problem.

Dan

what parts would those be? just the two hoses?

The two parts are the secondary air pump (number 1 in the picture below) and the valve (number 8) that is located towards the front of the engine. When I removed the valve, it was full of condensation.

Dan

http://i111.photobucket.com/albums/n...uy7563/197.png

first off let me say thanks for the response. Thank you!

i couldn't seem to find the part numbers for them on realoem.com

i looked in all HVAC catagories, i have a 4.4i, is it possible that my setup is different from what you described above?

either way im going to take a look around and see if i can find whats pictured above, check the hoses and see if that valve it fouled. i reset the alarm and it hasn't come back on but i dont want to cause more unnecessary damamge by ignoring the problem.

there was a black hose with a blue strip comming off that valve and it was all cracked up at the end. i trimmed about 1/2 inch off and reattached it. im going to clear the codes later on and see if it they dont come back.

i'm hoping that was the problem. it may be time to sell this one and get a newer one with CPO. anyone want a 2002 X5 with a working engine light. haha. seriously though, i love this truck.

I just got these codes...P0491 and P0492...I'm wondering how vital it is that I repair these...don't have much time at the moment...will it be okay for a few days? X seems to run fine. Also how difficult is it to replace these parts, any special tools?

Dear Bimmer Ese,
I also has the same problem. I did replace the #8 (second air valve) and #7 (the hose to the air pump). I am thinking buying the air pump.
In your thread, you replaced the pump, was it solve your problem?
Please advice.
Thankyou

Yes, the pump fixed the problem. Haven't had any problems thus far.

Dan

Thank you for reply so quick!
The SES light is not on any more after I replace the secondary air valve. My air pump went very noise in the morning, is your new air pump very quite? (I just want verify before I replace new one).
Did you have any problem with you engine beside the SES light on before you change the new air pump?
Again, Thank you for your advice

Mine had the exact same problem. Noisy pump and the SES light would come on after a few days from resetting the light. The new pump is quieter as compared to the old one.

Dan

Oh great....Check engine light came on this afternoon....P0491 and P0492 error codes again. I bet the smog pump or valve tanked. Perfect timing too....just a hair over two years, so no more BMW parts warranty =( I hope the light will not come on again.

Its an emissions device that pumps air into the engine during cold starts to assist in getting the cats up to temp. You're fine driving it till you get it fixed, but don't drag your feet on replacing it either cause cats aren't cheap.

BUMP, I've had the error for mine for over a year now and haven't bother replacing it. The pump does not make any noise (from what I can hear) or it's just quiet.. If the secondary air pump were to be the issue, i assume it would causes loud noises as people mentioned? Can I safely assume that since it doesn't produce any noise or minimal noise that it might be just a crack vacuum line?

I had same problem, the pump was tested and was fine, no vacuum leak, but apparently the metal tubing that carries the air to the exhaust can get clogged up with carbon or whatever. My mechanic ran water through the lines, got out all the debris, and now the codes are gone and no problems for 3 months.