Over the last 15 months, our vehicle has experienced unexplained stalling which has everyone, including the Mercedes dealership perplexed. Without any warning, the car will stall, either when driving or immediately upon starting the engine. The car appears to be fuel starved. Accelerating the engine with cause the car to die more quickly. Several hours later the car will start without any indication of a problem. The dealership has been unable to replicate while being serviced. To date, only once has a computer code been found in the system (resulting in the replacement of our cruise control actuator). I am beginning to suspect that this is weather related as this only happens during hot weather (temp. > 85 degrees). We have replaced the fuel pumps, over-voltage relays, diaphram pressure regulator, mass air flow sensor and have extensively tested electrical systems and fuel systems. Still, the car continues to stall every few weeks. I am desperate.

I would have the dealer replace the Mass relay. Do not confuse this with the Mass air flow sensor (HFM). The Mass relay is responsible for fuel pump operation and A/C compressor controls. I have seen them fail.


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Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM