Secondary Air Injection

[Paul B]

Does anybody know anything about Secondary Air Injection Pumps?

 

Mine is turning on intermittently on idle when the car is hot. I hear a relay click in the dash, then rough idle for a few seconds - during which I can hear the SAI Pump running. What sends a signal to it telling it is required? Is there an Air Temperature Sensor somewhere for it - perhaps built into the MAF?

 

I have been to 3 auto electricians (2 vw specialists) and nobody has found it yet as no fault code appears and apparently all sensors are working fine.

 

Any ideas?

 

Thanks.

 

Paul

Edited May 15, 2009 by Paul B

[sepulchrave]

What sends a signal to it telling it is required?

 

The ECU.

 

Is there an Air Temperature Sensor somewhere for it - perhaps built into the MAF?

 

No.

 

It is entirely a secondary emissions control system designed to help purge the Cat, disconnect it if you don't like it.