SLK/R171: Wiring Harness/ECU Issue - No Oil Found / After-Cat O2 Sensor Issues
Thread Starter
Junior Member
Joined: Mar 2017
Posts: 35
Likes: 15
2015 GLK350
Wiring Harness/ECU Issue - No Oil Found / After-Cat O2 Sensor Issues
Folks, I apologize for starting another thread, but once again I need help.
I have a persistent P0054/P0136 (Bank 1, Sensor 2) Codes for incorrect Heater Resistance/Voltage readings. R171 w M272
-At first I thought it was related to intake vacuum leaks ->Repaired those... code remained. (See separate thread)
-Then, I replaced the O2 Sensor ->Code remained.
-Next, I connected the driver side O2 Sensor, to passenger side harness connection, and vice versa...codes remained the same. (i.e., the issue followed the wiring harness/ECU)
-Next I learned about the Motor Oil in the Wiring Harness issue. But upon inspection, the car had sacrificial pigtails for the Cam Magnets, although not for the cam timing sensors. Regardless, I found no oil within any of the connectors, includin the oil level sensor, and the ECU connectors. I then pumped low pressure air "into the ECU connector", with hope of seeing oil come out at the other end "wherever the issue could be" -> so far, nothing!
I have spent a few hours researching furums, and other online sources. The charm.li diagrams don't really get me anywhere.
-Does anyone have a legible copy of the wiring diagram for engine/ECU for a R171, with a M272 (vin# WDBWK54F76F099257)?
-ECU Connector PIN list?
-Any other suggestions that may help?
At this point, my next thought is to attempt to isolate O2 sensor wires, and while at it perhaps decipher where interference could be happening.
Many thanks as always for your help.
My attempt to "push back oil agains capilarity effect", by pumping low air pressure onto the ECU Connector.
I have a persistent P0054/P0136 (Bank 1, Sensor 2) Codes for incorrect Heater Resistance/Voltage readings. R171 w M272
-At first I thought it was related to intake vacuum leaks ->Repaired those... code remained. (See separate thread)
-Then, I replaced the O2 Sensor ->Code remained.
-Next, I connected the driver side O2 Sensor, to passenger side harness connection, and vice versa...codes remained the same. (i.e., the issue followed the wiring harness/ECU)
-Next I learned about the Motor Oil in the Wiring Harness issue. But upon inspection, the car had sacrificial pigtails for the Cam Magnets, although not for the cam timing sensors. Regardless, I found no oil within any of the connectors, includin the oil level sensor, and the ECU connectors. I then pumped low pressure air "into the ECU connector", with hope of seeing oil come out at the other end "wherever the issue could be" -> so far, nothing!
I have spent a few hours researching furums, and other online sources. The charm.li diagrams don't really get me anywhere.
-Does anyone have a legible copy of the wiring diagram for engine/ECU for a R171, with a M272 (vin# WDBWK54F76F099257)?
-ECU Connector PIN list?
-Any other suggestions that may help?
At this point, my next thought is to attempt to isolate O2 sensor wires, and while at it perhaps decipher where interference could be happening.
Many thanks as always for your help.
My attempt to "push back oil agains capilarity effect", by pumping low air pressure onto the ECU Connector.
Out Of Control!!
Joined: Sep 2018
Posts: 14,666
Likes: 4,568
From: unbegrenzt
2017 GLE350 4MATIC
Capillary effect is not influenced by air pressure or gravity.
Capillary effect is a surface tension phenomenon. It cannot be defeated or counteracted. The leak needs to be stopped and the harness needs to be replaced.
Capillary effect is a surface tension phenomenon. It cannot be defeated or counteracted. The leak needs to be stopped and the harness needs to be replaced.
Thread Starter
Junior Member
Joined: Mar 2017
Posts: 35
Likes: 15
2015 GLK350
If you drive pressurized air backwards into a capilary tube (i.e., a fluid with pressure, and speed, and friction)..it will drive waterver surface tension has made the liquid climb up its walls! In any case, do you have answers to any of the questions posted? Thanks
