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Secondary Air Pump

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Sorry to bring up an old topic but I've been reading the previous post and haven't found what I'm looking for. I'm getting the 0410 OBDII code. My secondary air pump is funtioning on cold starts but I belive either as sensor or relay is going bad. The reason I belive this is because right before the CEL comes on, I can hear the pump kick off at what seems to be very early. The engine has not come to operating temp yet actually the temp guage hasn't moved at all when this happens.

Does anyone have the specs?

What temp should the pump kick out at?

Is this controled by an internal sensor / relay or is there an external sensor / relay that controls it?

Is it triggered by engine temp, exhaust temp or what?



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  • Admin

From the OBD II manual - initially temperature is a factor that turns the pump off - but the pump at run when engine is at operating temperature.

Through the secondary air system, additional oxygen is introduced behind the exhaust valves in order to reduce harmful emissions. This occurs after the engine is started, within a defined engine temperature range and for a predetermined time.

If passive diagnosis is interrupted, e.g. due to excessive RPM, then active diagnosis is performed at idle speed.

During active diagnosis, the DME switcrles the secondary air pump on when the engine has reached operating


Potential fault areas are:




air supply lines

or bad pump.

Edited by Loren
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  • 2 weeks later...
I had a problem with my secondary injection and it turned out to be the change over valve was not working.
This is by far the most common cause, especially if you can hear the air pump working. The change over valve has a vacuum diaphragm which goes bad. You'll find this valve under the intake manifold on back 1-3. You can test it by applying a vacuum and seeing if it holds. If not, you need a new valve. However, usually the change over valves failure is a symptom and not the real problem. A lot of times what happens is the non return valve (which prevents exhuast from the cylinder head going up stream to the secondary air pump) has failed and the exhuast has burnt up the change over valve. If you see corrosion or scorching on the one end of the change over valve, it would be very wise to replace the non return valve. Edited by PTEC
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  • 10 months later...

Does anyone have instructions on replacing the change over valve? My '99 base (59k) had an intermittent 410 code, then the other day the idle starts going crazy. At cold start it sits at 2200, then after a slight warm up it starts bouncing between 1200 and 1850 continuously. Cycles between these two marks about once a second. Does not stop after reaching running temperature. Now getting intermittent 410 and 1411 codes...

Thanks in advance.

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I had same problem with 0410 and 1411 codes. CEL was always popping up when engine was cold. I took it to my mechanic. Everything was in working order, except air valve. Problem was that over my 67K miles deposit build up very bad. the only solution was to take it apart and clean it, and that thing could be expensive(labor). He recommend to use BG44 cleaning kit, it's a three stage cleaning kit for intake and fuel system. I believe p-dealer can do it for 160$.

Since than I also started using Chevron Techron fuel additive for every single tank.

It's been over month without CEL.

I hope it will be more than that.

Here the link if you are interested BG 44K


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