SLK350, Secondary air injection fault

[stevebr]

Does anyone have any advice they could give me.
I have a 2005 SLK350 which has started to throw up a "secondary air injection" alarm (P0410).
This only happens when started from cold, if code is reset it does not come back (engine warning light) until the car has been started a couple of time from cold.
Have replaced the the air pump relay and switch over valve, as these were the cheapest components.
Still got the alarm.
Removed the air pump and both diverter valves, all looked ok, nothing came out of the pump (water/debris). Valves looked clean internally on the pump side and can here them close if vacumn is applied and released.
With parts back on the engine pump can be heard to run for approx 30 sec when started from cold.
Local garage has done a leak test on the engine, checked the pump and switch over valve say they are ok.
Also checked the 4 exhaust sensors (o2) and say they are also ok.
They suggest taking to main dealer to see if there is a software update for the engine ECU if not the ECU is faulty ?????
Does anyone have any experience of this fault or suggestions as to what to check next before it goes into MB.
Any help appreciated.

 

[smee2000]

Hi Just wondering if you got this resolved? I have the same problem also on a 2005 SLK 350, recurrent secondary air injection fault. About 2 years ago the pump was replaced. Recently the engine management light came on again, I had it reset a couple of times and then the pump was replaced (again) after relays etc checked. Light back on the following day. Fed up.

 

[AndyPCD]

When they replaced the pump did they replace the relay as this causes the problem usually

When you say they checked the relay etc what did they actually check on it.

 

[smee2000]

Aargh, thanks for your reply Andy, sadly I never saw it.

Don't know precisely what checks they did, but they said the pump was burnt out. "They" is an independent Merc specialist by the way. They replaced the pump. The warning light came back after about 25 miles. Took the vehicle back, they said the pump was burnt out again and replaced it again (under warranty). Warning light came back again, codes show secondary air injection fault again. Garage says, after further investigation, that all components are functioning as they should and I need to take it to MB to see if they can resolve it. MB have already told me over the phone that no software update is required, but that is all I can do now if I want this resolved.

Any suggestions appreciated.

 

[Auto-mobile]

Should always replace the relay with these pumps, I bet it's the relay from the start.