P0491 and P0492 wont go away

[mike_dmt]

I have the secondary air pump codes going. The blower is working, and I replaced the check valve and made sure the vacuum line is in good shape, and I zip-tied it on.

Still throws the code after a day. Any ideas?

[g300d]

What valve did you replace? The check valve in the vacuum line or the air valve attached to the cylinder head?

If blower works and you have confirmed all vacuum lines intact with vacuum and all vacuum line check valves working, that leaves the air valve to the head not opening, a clogged secondary air system air filter, or a defective secondary air mass sensor.

[mike_dmt]

Thanks for the reply, I replaced the one on the front of the engine.

There's a second one, AND a filter?

Anyone have an exploded view pic of the system?

I thought there were just the two major components, looks like it's something else.

[g300d]

Oh crap, just saw your sig, you were talking about a 4.4. The parts I referenced are for the 6cyl, sorry!

[crystalworks]

Here's an exploded view for you from an 01 4.4i off of RealOEM.


Maybe a clog somewhere? Or possibly the vacuum solenoid is faulty? Part number 1 in the diagram below.

[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

[Overboost]

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

Check your SAP relay. It failed on mine.

[trhaverstock]

Thanks for the lead. I am not getting good hits on an E53 X5 relay testing procedure. What other chassis has a similar relay (am seeing a lot of hits on e46) and where are the buggers located at?

[Overboost]

Originally Posted by trhaverstock

Thanks for the lead. I am not getting good hits on an E53 X5 relay testing procedure. What other chassis has a similar relay (am seeing a lot of hits on e46) and where are the buggers located at?

Bridge pins 30 and 87, the pump should run

[trhaverstock]

You rock! Will test this when I get home from work tonight. Am I following your pic that the relay is roughly behind the windshield washer reservoir?