a year ago I got the po410 code. Air pumps not working, so I replaced it & it lasted 1000 miles. That was an Ebay China pump so this time I bought a Bosch. Lasted one day & fried the pump & blown 40amp fuse. Tested the soliniods with a vacuum pump, replaced the vacuum lines. Checked my head passages. All seems ok?

also for some reason one of the vacuum lines comes from under the intake manifold. I broke that nipple trying to get the old hose off. So I blocked the hole & took vacuum from the top with a tee. Hope that doesn’t matter?

Thanks for the reply’s guys.
i started with checking the check valve. Then the vacuum functions. I then confirmed that the head passages were not blocked with carbon. Replaced all the rotted vacuum hoses.
Thats how I broke the bottom nipple.
anyways I found that the pump had power even when the car was off. It didn’t when I installed it. But I am thinking the relay finally stuck closed? I sent my rcm to Tighe for repair. Hopefully the vacuum source relocation won’t matter?

Hopefully I did. I didn’t find anything on our site about the head passages blocked with carbon? But found lots on Mercades searching. Maybe I should include that information in this post. Look for The large hose that goes from the air pump to the left & right head actuators. Remove the hose from each head actuator & start the car when it is cold. For 90 seconds you will hear & smell exhaust from the open actuators. If you don’t remove the actuator & retry when the car is cold again.
if you now hear exhaust then there is something wrong with the actuator function. If you still do not hear exhaust then the head is plugged with carbon. If the head port is plugged do a search on 2004 slk 320 sites & you will find methods to clear them & a more in-depth description.