rsalvo

I am beyond frustrated with this issue. I have gone through a series of fixes to clear the CEL and pass CA smog inspection. All are clear except the P410 even after a secondary air pump/relay replacement. The pump does its job on cold starts, runs for about 15-20 then shuts down. After clearing the codes and running a drive cycle (actually the monitor for this issue is reset after 2 cold starts) the CEL returns and claims the same P410 code. Mercedes service is starting to talk ECU replacement. Seems like helluva lot of money just to pass smog when all the "error" components are working properly.

How exactly does the smog test work? Does it actually measure smog levels or just read the OBD scanner error codes?

Rsalvo

rsalvo

Still trying to figure this out. The pump works as designed, came on this morning and ran for about 30 seconds then shut down. The OBD reader that I have shows (4) codes all related to the Secondary Air Injection System but, it does no provide detail, it's a cheap reader. A buddy of mine, BMW owner, said he had a similar problem caused by limited airflow due to carbon build up. His guy used Seafoam to clean out the system and the code disappeared.

Could this work if I can determine that the problem is limited airflow? How would I introduce Seafoam into the system? Anybody?

2012212

The output from the pump is controlled by two vacuum valves on the front of each cyl head. If these don't work because of a vacuum problem or bad valves is one thing to check. If they are working you can tell by unplugging vac lines to them while pump is running. The sound of the pump will change because the flow will shut off when vacuum is removed. If they are ok which is a pain because pump only runs for a short time. Techs can activate or jump the relay. Other thing is to follow the hoses from the pump to diverter valves and tap on them, they can stick.

rsalvo

Thanks, can anyone tell me where I can find a diagram of the system?

vanable

Also an FYI...if your car is a 4Matic, most CA smog check places don't bother doing a dyno and sniff test anymore; they'll just plug their computer into your OBD port and test it that way. So no need to worry about "warming the car" up and all that jazz anymore...unfortunately, emissions-related codes WILL be a problem though.