Check Engine Light seems to be a common problem on MBs and other cars. Advance, Autozone etc all provide free check of codes and resetting.
On our MB, I get told that problem is likely the MAS or O2 Sensor or wiring harness. However, there does not seem to be an easy way to just test a sensor and find out if it is good or bad. Dealers just want to replace parts whether needed or not. These things are not cheap!
Does anyone know whether or not Bosch or MB offer a service to actually test the MAS or O2 sensor? It should not be difficult or expensive to set up a test bed that checks the signal.
How about the wiring harness - Is it just the plugs that would be faulty? If the wires themselves were bad or broken, you would not think the car would continue to run properly.
Another thing that puzzles me, is that after the CE light comes on, the car still runs perfectly. Surely the MAS must still be working if the engine runs well, does not misfire and gas consumption remains normal?