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Old 06-02-2020, 09:52 PM
Fruitsalt Fruitsalt is offline
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08 328i, n51(SULEV) P0492

Hi guys

I have a 2008 328i, with an N51 SULEV, Unfortunately the car is out of the SULEV extended warranty.

Every second cold start it throws me a P0492 code ( Secondary air insufficient flow bank 2). I have tested all components on the secondary air system and everything worked as it should. Even then to eliminate my missing something I've replaced the following parts with new genuine bmw parts:

1) air pump
2) relay
3) valve
4) hose from pump to valve
5) upstream oxygen sensors

I have confirmed that the pump runs, physically as well as using ISTA, checked the valve as well.

I have been able to set the SA monitor using ISTA and it passes all tests that ISTA does, finding no faults only to give me a check engine light on the second cold start

I have also checked for the ports being clogged. With the valve off and engine on I can feel the exhaust coming out of each port(engine cold). I also ran smoke/air thru the port on bank 2 and can see the smoke/ feel air at the exhaust tip.

What am I missing?
Could this be caused by a vaccum leak on the PCV, since it connects to bank 2? Or a bad MAF ? Or could the ports be clogged inside, if so how would one clean them.

Any help would be appreciated
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