Mystery Fan Motor

I had a check engine light diagnosed and was told the cause was a dead fan motor used on cold starts to circulate air through the catalytic converter.

Does anyone know what the name of that part is?
The guy at the shop that diagnosed the problem is on vacation, so I'm in the dark for more than a week.
I've been through the service manual on the exhaust system and have no idea what the guy could be talking about. I've had this '01 E38 for about 6 months and was thinking this could be my first DYI project. I just can't figure out exactly what part to replace.

Any ideas???

Secondary air pump is the name.

Sounds reasonable.
Many thanks!

I just had mine replaced with a Rebuilt unit from a shop on ebay(Volvo something or other) but also replaced the control valve with a brand new unit from Bavarian Autosports. it starts 3-4 times in cold weather, then resets the SES Light... I'm thinking It might be a bum Secondary Air Pump...