02 325i Air pump and diverter valve

The check engine light came on so I took it into the shop.. Turns
out that theres a air pump and a diverter valve that inject into the
exhaust system to burn up extra hydro carbons. They want to charge me
$550 for parts and labor ot replace both the pump and the valve.....

Does anyone know anything about this?

Does that price sound right?

Thanks
.