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Discussion Starter · #1 ·
I have a 2000 vw 1.8T. I had the dreaded p0411 code solved. But now my secondary air injection fan won't turn on. I checked the 100 relay by jumping the connections to turn on the fan which it did. I also check the relay by connecting voltage to the relay small pins which gave continuity on the large pins. What sends voltage to the relay?
 

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Have you scanned the car again; any more codes? If you have a VW scan tool (e.g. vag 401 or VCDS); you can try to activate the sai system with output tests, check out this video for more info:

https://www.youtube.com/watch?v=lbLZaf6QPQE
 

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Discussion Starter · #3 ·
Thanks nice video. I have replaced the fan motor, the combo valve, the vac relay that opens it. It was all working but now the pump does not come on when the car is cold. I can jumper it with the 100 relay out. The relay is good. I have a basic code reader and there are no new codes. I would like to know what powers the relay 100. Is there possibly a fuse associated with it?
 

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Keep in mind the SAI system will typically only run on cold start, first thing in the morning. It may not run on other cold starts later in the day depending on the engine coolant temperature.

I have not studied the VW SAI in great detail, however, other German cars typically will not run the SAI if the engine coolant temperature is over 104F. So make sure your engine coolant temperature sensor is reporting correctly.

The other major problem with the SAI on the 1.8t is the hose breaks just at the Combi valve back near the firewall.
 

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cambi valve

another common problem is the plastic part of the valve get's gunky inside and start sticking. Before buying one I would just remove the one you have there and clean with plastic safe cleaner, cycle it with a handheld vacuum pump and re-install.
There ya save u-self some Monies.:D
 
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