2000 Catera Check engine code "P0411"

Just_me · #1 (**permalink**) 05-10-08, 02:05 PM

I have a 2000 catera with 84K miles on it and suddenly the check engine light comes on. The error code that comes up is "P0411" which stands for Secondary air injection system incorrect flow. I really need some assistance with this one because i'm not sure what this is and what to check. Please help! Thanks!

1998catera · #2 (**permalink**) 05-10-08, 10:44 PM

This can be soo many different things that this could be. For me, I would clear the code and it would be off for a day or two. I never had anything else be affected by it, so i let it go. When I had my cooling system redone, they found a tiny hose that cost me $0.98 that had a pinhole in it. A pinhole. That's it.

I'm not saying this is something that you have, but it could be. I also looked into it being a defunct gas cap. For me my Check Engine light was on for about a year before I happened to get it fixed.

Matt

wildrage · #3 (**permalink**) 05-10-08, 11:30 PM

It is the secondary air injection system. There are only a few things it could be:

The secondary air injection pump
The air check valve
The air control valve
Any of the vacuum connection leading to the air control valve.
O2 sensors (although unlikely, they usually throw a code on their own)

The pump is located on the bottom of the driver's side front fenderwall. It has a hose leading up to the air control valve. This valve is mounted to the fan on the radiator. The valve has 2 or 3 vacuum ports on it. Make sure each port is plugged in, and that the port that it leads to (I beleive they all go to the air intake setup near the throttle body) is connected as well.

The secondary air injection system is purely an emissions device. It injects air into the exhaust manifold when the car first starts and when it's been idling for more than a minute. The newly introduced air causes the 02 sensors to run lean. If the computer does not see a lean condition it causes the P0411 code. This is why it could (but probably isn't) bad 02's. I think it usually throws the code after 4 or 5 missed readings..usually a day or 2 after the code is reset (with normal driving).

If it were me I would do the following in this order:

1. Check the connections to the Air control valve, which is bolted onto the radiator fan between the radiator and the throttel body (slighty off center towards the driver's side).

2. Check the hose going from the AIR pump to the Air control valve to be sure it's connected.

3. Verify that the AIR pump is operational (either by hooking current up to it or waiting for it to come on). They sometimes may suck in water, as they are located towards the bottom of the car - this kills them.

4. Replace either the air control valve or the air pump, depending on how your tests go. They are relatively expensive, but won't totally break the bank.

Hope this helps.