W202 C230k high idle issue

Page may contain affiliate links. Please see terms for details.


New Member
Jan 10, 2016
Mercedes 190e
Hello there,

I'm having a real issue with trying to track down the source of an idle/running issue with my W202 C230k.

The car idles at between 1500 and 2000 rpm. The throttle body pulses within its idle control sweep, and the bypass valve doesn't activate at all, or kick in when the revs increase. If I unplug the throttle body, the idle drops to around 1100-1200 rpm.

I've changed a host of sensors and parts, including MAF, OVP, Camshaft sensor, IAT sensor, Coolant sensor, Throttle body (rewired both the original and the replacement), supercharger bypass valve, fuel pressure regulator and coil packs. I've made sure the battery is fully charged, made sure the rest of the wiring loom isn't degraded, and checked for corrosion in & around the ECU, and checked for pushed out pins on the connectors. I've also changed the fuel filter, and assured it has fresh fuel. The immobilizer/alarm is also bypassed and removed. The fuel filter is audible from the drivers seat, so assume this works too. If I have a significant vacuum leak, I can't for the life of me find it. The crank sensor is in working condition, and the car won't run if I unplug it.

I'm totally, totally stumped. Do you have any suggestions that I've missed?

I tried having it plugged in with more generic equipment at the local garage, which didn't show up any codes.

The car is a pre-facelift, manual chassis.

Any suggestions past 'plug STAR in' would be hugely appreciated.

Users who are viewing this thread

Top Bottom