C5 - Check Engine Question

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Mike - 08 Nov 2005 00:41 GMT

Have a 2000 C5 and I have been receiving an intermittent check engine
light for a few days now. Went to Autozone where they did a error code
diagnostic and found out it was P0401 - Secondary Air Injection System
Malfunction. Anybody know how serious this is? Is this something I can
take care of or does it need to go to a dealer. Did some searches on the
Web but came up with very little. Any help would be appreciated.

Thanks,
Mike

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Dennis Willson - 08 Nov 2005 01:12 GMT

Does the light come on right away after you start it or after the car has been running a while?

The AIR system basically blows air behind the exhaust valves for a some amount of time following cold start. This adds oxygen to the
exhaust, initiating a secondary combustion and thereby shortening the warm-up phase of the catalytic converter.

The code is not really specific enough to determine the type of malfunction. You would have to look at the trouble shooting
flowchart that's in the factory service manual. You do have one don't you? I always buy the factory service manual for all my cars
and hope I never have to use it. But for things like this they sure are handy.

I could be anything from a loose wire for a sensor or the pump itself going bad.

Dennis

> Have a 2000 C5 and I have been receiving an intermittent check engine
> light for a few days now. Went to Autozone where they did a error code
[quoted text clipped - 5 lines]
> Thanks,
> Mike

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Mike - 08 Nov 2005 23:26 GMT

Dennis,
The check engine light first came on when I was driving and stayed on
for about a day. It remained on when I started the car the following
day. It went off sometime in the middle of the day. A few days later it
would come on again and follow the same pattern. Currently the light is
off. Unfortunatly, I do not have the factory service manual. So I guess
your telling me I need to take it to the dealer.

Mike

> Does the light come on right away after you start it or after the car has been running a while?
>
[quoted text clipped - 18 lines]
> > Thanks,
> > Mike

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Dennis Willson - 09 Nov 2005 00:24 GMT

Yes, the code is not enough to know what is really wrong. Actually this is most times the case. The code takes you to a flowchart of
how to determine what the problem is. If you don't have access to that you need to go to the dealer.

Funny what they test and put in codes and what they don't. On my 93 C4 it had a test and error code for the backlight on the
frequency display on the stereo. So if you change to an aftermarket stereo... it throws error codes all the time which appears on
the dash as "SYS" every 15 seconds! I finally fixed it by putting an LED attached to the wires that powered the little display and
the problem went away. I thought (still think) that this is a really stupid thing to monitor! Like I wouldn't notice the light was
not on! Like no one will ever replace the stereo with an after market unit. Worst yet... Since it only displays "SYS" to the user,
if you didn't know how to pull your own codes and look them up, then read the trouble shooting section, you would have to go to the
dealer to find out that the light in the stereo was out (even though you could see that it was not on)!

Dennis

> Dennis,
> The check engine light first came on when I was driving and stayed on
[quoted text clipped - 28 lines]
>>>Thanks,
>>>Mike

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