I just purchased a 1999 ML430 and my check engine light is on and has only one codecausing the light to come on and it isCode PO410 for the Secondary Air System. I looked up the codes for the car and am not sure whereto start the trouble shooting. Air pump, fuel pump,vacuum leak, O2 sensor??? Any help whatto do with this would be greatly appreciated. BTW: the car runs fine...but I don't want this to cause other problems.

 

could be a few things check your air injection pump its that big black thing mountd to the front of your motor see it there are is a hose that has poped off of it sendont make sure its coming on. i have need where the air pump relay does stick the contacts in the relay burn up

 

I checked to see ifall of the hoses are connected to the pump and traced themback to ensure there were no brakes in the lines.All OK.

How do I check the relay? Where is it located? How often should the pump come on?...or does it run continious?

Please help....

Thanks,