Secondary air system

[cn90]

Found it, the Walmart air pump for $18 in E39 forum...


P0491 - Secondary Air Flow Pump...fixed for $18 - Bimmerfest - BMW Forums

[ArmyX5]

Originally Posted by cn90

Thanks for the update.

PS: The reason the pump fails so quick is that: it spins at very high speed (? 5000 rpm or so) like a hair blower. It spins for about 30-45 sec or so on cold start.
The electrical motor is made by Johnson Controls and you bet it right, it is made in China.

I must be one of the lucky one! Mine has 148K Miles/10years and still going strong(crossing my fingers). I did replaced the secondary air sensor and the valve once.

[hunds02]

I finally had time to work on this yesterday. I figured out that the valve was damaged or seized up as no air was coming out the valve when I disconnected the pressure hose. The link below is very helpful for diagnosing SAS problems:

BMW Secondary Air System Fault Code Diagnosing How To DIY OBD-II | Bavarian Autosport Blog

Also the code originally pulled up was 5E on the Peake code reader which is SAS air mass. I double checked with a generic code reader and I got P1419.... SAS air mass. I purchased the a VDO air mass sensor and also replaced the air filter element and both the pressure and suction hose.

So pretty much every component in this system was replaced yesterday, except the air pump itself.

Now the air pump did not start this morning!!! Before swapping all the components, the air pump would only run for 5 seconds rather than 45-60 seconds. What could I have possibly done wrong that the air pump would not start anymore?!

Does anyone know if the gasket to the valve has to be installed in a certain direction? Its really flat but not 100% identical on both sides. Could installing it in the wrong direction cause the pump not to kick on?

[StephenVA]

Loved that solution!

[hunds02]

Originally Posted by StephenVA

Loved that solution!

It wasn't a solution! Now my pump isn't turning on!!!

The next step will be to apply 12V to the pump directly to see if it will turn on. If it does then I have to check for fuses or relays and check the pump electrical connector for 12V on cold start.

Any other suggestions?

[StephenVA]

I was referring to the Walmart hair dryer solution.

The gasket should align to the holes on the flange to allow no blockage when installed.

Test to see if the pump runs disconnected from the supply side and or the delivery side.

[StephenVA]

test two
Pull the diverter valve to confirm operations (the chrome looking thing that switches air down stream) Operates on a vacuum source (Does it receive a signal from the vacuum hose?)

The only thing I have ever seen is a collapsed hose or the pump locks up due to age dirt etc

[hunds02]

Went out for lunch today and I guess four hours resting in the sun was enough for a cold start. Cranked the engine and not only did the air pump kick on like it was in the past, but this time it stayed on for a complete minute rather than 5-10 seconds.

Why it did not work this morning I will never understand. I did not do anything to the car today besides drive it to work. The SES light did not come back on.

I guess the system is fixed now! After I drive for about 100 miles I'll get my emissions test as I am due for it this month.

Thanks for the help everyone

[davesx5]

I also had a air pump problem like this. Mine would run once in a while. Finally I removed the air pump, wired it up on the bench and let it run. It only ran for 5 minutes then tied up. Once cooled of, it would run again. I installed a new pump, all runs great.

[hunds02]

Do you think that a faulty air pump or one that's on its way to go out will cause failure of other components (i.e. the valve or the air mass sensor)?