The MAS relay has 5 functions & shouldn't have any effect on HOW the engine runs.
MAS controls; fuel pump, a/c compressor, air injection pump, O2 sensor heating, & kickdown.
If the MAS relay has a problem then the car shouldn't start OR the check engine lamp should come for the O2 sensor.
The CIS computer must get power from OVERVOLTAGE relay & must apply current to the EHA for the car to have a good cold start. See above posts!!
MERCEDES Benz Master Guild Technician (6 TIMES)
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