Hi there,

so I had my check engine light code read at a friendly mechanic and it came back with P0150: o2 sensor (bank 2 sensor 1). Reading some discussion groups, I figured bank 2 sensor 1 is on the left (driver) side, sensor before the cat. My question is how in the world do you get to that thing on a 2000 CLK 430? I can hardly see the two connecting wires and reaching the sensor seems impossible. Do you go from down under? Anyone's done it and can share the experiences?

Thanks,
tomasz.

 

Never mind. Looked from under the car. Easy access.

Cheers!

tomasz.

 

The code you quote is a GENERIC OBDII code which identifies O2 Sensor Circuit Bank2 Sensor1. This does not necessarily mean that the sensor is dead. Many sensors get changed unnecessarily. Any other codes stored or pending?

I'm not 100% sure on your car since you don't state which Market you are in, but the sensors (2 per bank) are located Before and After the precat (small) mounted nearest to the engine exhaust manifold. I suspect that you are looking at sensor 2 adjacent to the gearbox.

Get your "friendly" mechanic to run a voltage test on the offending O2 sensor to determine what voltage it is giving off and compare this with the one on the other bank. IF it is different then either the fuelling or the sensor is bad.

IF you go ahead and decide to change the sensor without further investigation (many people can't be bothered to confirm diagnosis!)...I wish I had their bank balance...ensure you buy a genuine MB O2 sensor or at least the recommended Bosch one rather than some cheapy "fits all" which you MAY discover is the start of a whole host of other problems.

I suspect that it isn't the sensor itself but the wiring/connector etc. My experience suggests that a hugh number of sensors get swapped out unnecessarily. If however you have done high mileage OR the other sensors are also giving similar (poor) results than maybe you have had a bad batch of fuel and all sensors have been adversely affected.

Let us know how you proceed.

Stuart.

 

The sensor is most likely the problem. In fact, at the dealership, when checking for codes with SDS, Mercedes pays no diagnosis to the technician when an oxygen sensor code appears when the car is under warranty. They only want the sensor to be changed automatically because the failure is so common.

 

Thanks for your responses... I just wanted to follow up and let you know that changing the O2 sensor did the trick and the check engine light is now off.

Thanks again,
tomasz.