I HAVE A C230 KOMPRESSOR THAT IS MISSFIRING IN CYLINDERS 2,3,4
I HAVE CHANGED FUEL FILTER, CYLINDER 3 INJECTOR, TEMP COOLENT SENSOR, AND A FULL TUNE UP.
WHEN I CHANGE THE INJECTOR PROBLEM WENT AWAY FOR A WEEK AND CAME BACK.
MY CHECK ENGINE IS ON ALL THE TIME AND CAR HAS NO *****.!
THERE ARE FAULT CODES AS SUCH.
1- CYLINDER 2,3,4 MISSFIRE AND FUEL DEFFICIENT
2-TEMP COOLENT SENSOR
3-CAM SHAFT SENSOR
I HAVE GIVEN UP AS MERC BENZ DEALER CANT REALLY FIGURE IT OUT

 

2003 had multiple problems and yours may have 2 of the 3 below (you pick)-

1) a defective head. It may need to be replacedwith a new one and it will be fine. Figure $1,500 or so if you buy it online and do it yourself, or about $3,500 if a dealer does it, maybe $1,000 less if you find the right independent. What happens is carbon builds up on the valves and causes the misfires.

2) defective camshaft sensors that leak oil into the wiring harness and corrupts other sensors, usually the O2 sensor. They have a cable extender that helps mitigate this problem specifically for the 2003.

3) Valeo radiators leak internally into transmission lines and wipes out the transmission.