96 M119 eng runs great but keep getting code 410 secondary air injection malfunction. I have replaced all o2 sensors,the air relay K17,ECT sensor.
The Air pump runs on startup for about a min.It also runs for a short period when the temp comes up over 80c (closed loop).
My snapon mt2500 will not turn it on when you go to actuator tests unless the eng is off (weird?)
I can run the pump all day with eng off with the mt2500 tool
so I can not check the o2 sensors drop below 40mv.
Shutoff valve works good tested it with vacum tester.
Electric changeover works tested it with 9v batt and vac tester .
Removed Air pump and shutoff valve blew air and smoke in and it comes out the exaust so ports are not cloged in heads.
Found the inlet screen for air pump totaly cloged with grease and dirt,so I cleaned it.I also poured some injector cleaner in the pipe and blew it out the exaust it came out in a fine mist from tail pipe.
Can I test the pump for air flow and what else can I do b4 putting this thing back together tomorrow???
Can the pump work but not put out enough air???

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88 W124 3.0
96 R129 119eng
06 ML350
98 ML320 sold
02 CLK55 amg