JLee81

Both of my rear sensor wires were extended because of header installation.
After install, I keep getting O2 malfunction in the rear sonsors. Should I replace them? or try to clean? I drove the car with the sensors unplugged in a rainy condition. help me please.

sosh

Could be that the additional resistance of the longer wires and the splice will cause the O2 readout to be out of limits. I suggest that you remove the headers, put it back to stock and use the original length wires to the sensor. You became a test pilot and the aircraft crashed!

mleskovar

You installed new headers and extended an electrical connection a foot or two and now get a sensor failure and think it's because of the added wiring? How about the efficiency (or lack) of the headers? Is that all you did?

sosh

I, not the original thread starter said it may be the wireing length/splice. But you may also be correct that the headers may in fact have something to do with this. I get a charge out of these guys that hack into their vehicles with absolutly no understanding of what the consequences may be. Many of them end up hacking even more to solve what ever problem they have created and then blame MB.

JLee81

I installed headers from kleemann. They told me that it would work fine if all the wires are connected properly with 18 gauge copper wire. Well.. Now i really should start thinking avout putting back the stock.

Cory @ Kleemann

There are 4 things that can cause this fault:

short to positive
short to ground
open circuit
intermitent contact

Whoever did the wiring either did a very sloppy job, or got the heater circuit wires mixed up (there are two white wires, a grey and a black). I have this same modification on my CLK430 and have never had a problem. After 70,000 miles, it even passed our local IM240 E-test with flying colors. Sounds to me like it's time to go back and check, re-solder and insulate the connections. Remeber, there are 16 chances to get it wrong.