fault code for 96 E36

[Bobs96]

Check engine light came on. I bought scan tool. Fault code F6- Secondary air system flow too low. What do I do now?

[Manolito]

On the exhaust side of your engine back behind the shock tower is what looks like a a vacuum cleaner motor. The air inlet tube runs forward to near the radiator external reservoir. A hose carries the air from the fan up to the front of the exhaust manifold where there is a check valve that keeps exhaust gas from pushing back to the fan.

If you open the hood and have someone start the engine when it is cold, you should hear this fan turn on run for a couple of minutes until the catalyst gets warm.

These fans usually get really noisy and make a high metallic chattering sound just before they fail.

If your fan has failed, you can ignore it. It will not affect the way the car runs. It won't pass an emissions test, however, with this error code stored.

Often, these fans fail prematurely because the check valve fails, and hot wet exhaust blows back through the fan, spinning it backwards and filling it with condensed water. Disconnect the hose between the check valve and the fan and start the engine. If exhaust comes out of that hose, or if you find your fan full of water, the check valve has failed.

There is a place on eBay the rebuilds the fans for BMWs and Volvos (their ad just says Volvo, but they are the same fans) for about half the price of a new fan. The check valve is not rebuildable. If the check valve has failed, you will need a new one.

When you remove the fan, be careful of the soft rubber mounts that hold it in place. They have flats so you can hold them with a wrench while you remove the nuts. If you don't hold them, you might twist them in two when you try to remove the nuts. Not a big deal, the rubber mounts are not very expensive. The fan and the check valve, however ARE expensive (sorry). A new fan is about $310 on line, and a new check valve is about $125 on line. I did not look but I am sure Pelican has them because this is a common failure part on cars this age.