Denso and NTK you can easily solder/heatshrink. Bosch you cant. The change in resistance/material of connector is brought up a lot. On a 4 wire oxygen sensor, the circuit resistance is so critical, the pins on the 2 sensor wires are gold plated, while the heater circuit is a regular pin. Since the o2 sensor is the generator of power in the circuit and there is no load on the ECU side, the loss of voltage through wire resistance is negligible. The issue I run into with disco's all the time, is cross contamination from the heater voltage/ground and the reference ground from the PCM to the sensor signal wire. Since the o2 is the generator, it creates extremely little current and thus the voltage is extremely easily manipulated by water/oil/dirt in the plug allowing continuity to the other wires in the plug. What I've found is that this more than anything causes oxygen sensor faults on disco's. Seems like the silver bullet is to separate these wires and solder/heatshrink or heatshrink crimp with pink connectors.

 

For your benefit Whiterabitt, After I completed my HG repair the code started on the DS. I replaced the O2 as all sorts of junk was on it. The new Walker sensor tossed codes as well so I thought it might be an issue with my splices. Went back, redid splices, checked continuity and voltage. All looked good. Started car and within 30 seconds started tossing codes on both sides. Passenger side wiring was not touched in any way during the project so that is a big mystery. Put in 2 brand new Bosch O2's and still have the same problem. Wiring checked multiple times. What I might do is get a pair of Walkers again and see what happens, as I have had Bosch O2's be bad right out of the box. In my 10 years of own this beast, this is the first time that the no voltage codes have popped. There is a rover specialist I am going to take it to when his schedule frees up next week. Between now and then I may just give it one more go with Walkers.

 

Matt, how good are you at darts?

 

I'm sure your clients find that an interesting testimonial to your skill set.