Hi.

Is there any sense to change my catalisator if I have O2 sensor fault after cat continously even I changed the senor?
Basicly after I clear the errorcode I can drive random km before it popup again.
Usually it is happen when I use engine brake.
The car is also using a little bit more oil nowdays what is not solved yet. Maybe this is also matter because the sensor measure wrong signal because the increased oil amout in the exhaust system.

So the question where I need help:

1, Change the catalisator first or try to solve the oil consumption issue?

Thanks a lot.

Br. Gábor.

what exactly is the error?

It might be the sensor, it might be the wires from the ECU to the sensor.
You also need to use something like MES to graph the sensor's readings to see if it's working.. and if the CAT is working ... you can get a pretty good idea..
You can also see more detail on the error.

It doesn't make sense ... because in engine braking the injectors are not opening... so there should be even less gasoline in the exhaust.
.... so maybe a short to ground (maybe on the sensor heater circuit).. making contact only under engine braking because of the additional engine movement.

How much oil is it using? if it's anything under 400ml/1000km you don't really need to do anything about it because it would be in spec.

Is this case my oil consumption looks normal.
I thought that if I need to refill 1 liter after 5000 Km is a bad sign.

To tell the truth I already checked the signal with MES but nothing special is visible. I'm affraid it will be a hard job to catch this fail.

But anyway thanks for your comment. I will not change the catalisator until I'm not 100% sure it is not the sensor.

Thanks man!
It was really usefull.
I watched the video so for sure I will check the O2 voltages soon.
If you are interested I can post the result here later.

Please post back.. it might help someone else.