SLK 230 Check Engine Light

I am taking my SLK 230 in for the third time to fix whatever the problem is that is causing the check engine light to go on. They are finding a Code P0410 (air injection secondary system malfunction). The last time it was in the mechanic disconnected a switch at the front of the engine that he said controlled the air flow to the front of the catalytic converter and hooked up another one that was mounted there. Apparently there was a spare (in-line) switch. This was ok for a week, then the light came on at startup. Apparently that wasn't the problem. Anyone have any ideas? The engine seems to run fine.

[PJozefiak]

My SLK is a 99 and I am having the same problem. What year is yours? So far I haven't been able to get it checked. It has gone on 4 times now, for two or three days at a time, and every time I resolve to call the dealer, it goes off. Car runs fine. I think it's one of those tree huggin' O2 sensors or something thats gumming up the works, but my fear is that by the time I make an appointmet and get it to the dealer, he won't be able to get the problem to reoccur.

[JimF]

Had the same problem with my '94 S500. DTC was "AIR injection inoperative".

The injection pump was operating ok but still the MIL would light.

Checked the vacuum lines from the manifold to the AIR injection switchover valve (Y32) and the shared check valve between the AIR and EGR switchover valves (Y27).

Took it apart and cleaned 'everything' including the AIR injection shut-off valve mounted on/close to the manifold.

Sometimes just dirt/carbon, etc. and a little inspection or cleaning does the trick.

The part numbers may be different for your car, so may need a CD-ROM or some schematics. But the theory is probably the same.

[Gilly]

See if you can ask for a different mechanic to work on the car, this one ain't cutting it!! The system works essentially the same as the 94 S500 (JimF's car), as he mentioned, with one critical twist: the supercharger acts as the AIR (air injection) pump, it has no seperate pump dedicated to the task as a S500 would have. It is a quite complex system. No need to assume a O2 sensor glitch, they are quite able to set there own set of codes, and often DO! I can't tell you exactly what is going on with your car just by having the code. As far as JimF's comment about dirt/carbon, etc, this is a very "clean" system, especially on a Kompressor, but in general. Often times the AIR system will be confused somehow with the EGR system, which of course is the dirty business of redirecting pre-cat emissions back into your intake tract. EGR systems can be a plugging concern, AIR typically isn't a problem, unless the divert valve sticks open, and even then the problem tends to concern getting condensation water into the pump, not the carbon from the exhaust. I don't have a clue as to what the mechanic was telling you he did, sounds like some kind of nonsense double talk to me.......Gilly

[Nektopoli]

Had this just happen to my 99SLK with about 61K miles on it? Should I just take it in to the shop?

NP