Hi

This car has got me running around in circles!

This car is running very rough at idle and at standstill is very reluctant to rev, some times chuffing back through the inlet.

The garage had already changed the throttle body for a 2nd hand one and the O2 sensor had been change for a new one.

DTCs are:-
P0170 Lambda Control : Self adaption is too rich
P0130 O2 sensor upstream TWC. Minimum voltage not reached

I have scoped the O2 sensor and found that it does not switch at either pin 23 or 24 at the ECU, even when I add some hydrocarbons or induce more air into the inlet. When I do add hydrocarbons the engine picks up. [sorry, no gas results available]

Fuel pressure and flow, good.

I have checked the wiring between the O2 sensor and th ECU, and I have tried the original O2 sensor and it is no different.

My question is, do these O2 sensors switch normally between approx 0.1v to approx 0.9v or do these use milli amps? Merc WIS says its the normal switching but I wanted some more advice.

On live readings the O2 control before TWC is 1%, when the system logs the DTCs it changes to 30% and runs a little better in limp.

Any help would be great.

Regards

Simon