BMW Repair: 2001 BMW 325i - P0491 & P0492, 2001 bmw 325i, bmw 325i

Question
There was an answer in November of '06 answered by "Tino" regarding diagnosing P0491 and P0492 codes.  I would like to know why my service engine light was on in the summer, then went off when the temperatures were mild, and now that it is pretty cold in the morning, the service engine light is back on?

Answer
Sounds like a secondary air pump problem. The SAP comes on for 60-90 seconds at cold startup to help burn hydrocarbons in the catalyst on a cold start. Usually water in the pump due to a failed check valve. Sometimes can burn out if the relay doesn't shut it down after 90 seconds. Check to see if you SAP fires up (located in front of right front wheel) on a cold start. If it doesn't, then that's your problem. You can run the car without a functioning SPA as it does not affect drive-ability. It just won't pass an emissions test (clear the codes before an inspection). SOP is to replace the valve whenever you replace the SAP. Kinda pricey repair (SAP ~ $250+ and valve ~ $80

Tony