wiring looms 104 engine

[docmercquad]

Hello,Everyone talks about disintegrating wiring looms on the 124 E320 engines. This is to do with the loom that supplies the coils, injectors and runs over the top of the engine and is labelled connector2. What about the other main plug from the ECU that supplies the fuel pump and the oxygen sensor and is labelled connector1. Do these degrade as well? My 1995 E320 has failed the emissions test and there is only 3 volts at the o2 sensor heater supply wire. I assume there should be full battery (12 volts) here. Anyone got any bright ideas?
Thanks.

 

[carat 3.6]

It is the entire loom that fails, if one part is bad the rest wont be far behind.