Originally Posted by trhaverstock

Hello all - I have a "new" 2004 X5 3.0 with just over 89,000 miles. The first BMW I have ever owned. Two days after receiving it threw P0491 and P0492 codes together. I poured through the forums here and also watched several Youtube videos. I need a little help in the right direction on next steps. A lot of the FAQs are around the Secondary air pump check valve that has a vacuum line on it - mine does *not* have that. I removed the pump itself and connected 12 volts - it runs great; sounds right. I removed the check valve and cleaned with brake fluid. I removed the sensor and cleaned with MAF sensor aerosol spray. The last morning it was cold, around 35 degrees, the system will not kick the pump on - I am not hearing it running. I think that is a key clue here. I am leaning towards replacing the check valve but I don't want to waste money if that is not likely to fix it. All electrical connectors seem to be solid. This vehicle overall is in outstanding shape for it's age. And a manual trans! Thanks for your help. -Todd