Hello! I'm back! I've been working on my 02 disco 2. I recently have been redoing all of the emissions because of a front driveshaft coming apart. New Y-Pipe, all 4 new Bosch o2 sensors, and fixing some previous owner repairs(o2 wiring). I keep getting a P0134 code and an emission code. The o2 with the issue(throwing the code) had a hacked harness. I repaired it with the correct connector, etc. I swapped the front o2's and even tried a new one. Watching the live data, I saw the same issue again and verified the o2 was OK. I keep getting .450-.460 volts from the bank 1 sensor 1. I checked the voltage coming in to the connector. One wire had 12v and the other had .45-.48 voltage. The other 2 wires had no reading. When I plug the sensor in, I am getting the same voltage in and out of all 4 wires at the splices I made. 12v in/out of the 2 wires dedicated to the heater circuit and .45-.48 in/out of the ecu input/return signal wire. I would like to check the voltage at the ECU return wire but I cannot figure it out on the RAVE. Which wire(color, location, etc) should I check at the ECU connector? For some weird reason, I have a gut feeling they mixed the wiring up previously and damaged the ECU...

PS: If it is the ECU, I have heard it is not as easy to swap in a new ECU. Am I wrong?

Thanks all!


UPDATE!
All wiring at the o2 connectors are good and o2's are good as well. NOW, I thought about it and I have not checked the voltage as it was running. Only with the key to the on position. It is hard to get to the splice I made when that manifold is hot. Does anyone know which wire and location of said wire to test for return voltage at the ECU/ECU connector.

 

Did you rewire the vehicle side of the harness or the sensor itself? I just rewired both the drivers and passengers side o2 harness on mine and in the process figured out that both of my Bosche O2's ( both less than 6 months old) weren't functioning correctly.

As far as input/outputs at the sensor. With the sensor plugged into the vehicle, you should have two leads with 12v, one with .45 (or very close to it) and one that varies between .1 and .8 ish when the sensor is warm. If you have constant .45 volts on the reference circuit, after several minutes of engine running, then your sensor heater or heater wiring is bad.

​​​​​​I recently changed my computer. You have to change the ecu, slabs, and cluster all at once to avoid issues. It's really not that bad.

Let me see if I can find the pin out diagram for the computer. I should have it saved to my phone

 

 

I rewired the connector on the harness side. NOT the o2 side. Brande new o2's. Noticed it was fluctuating normally when I put the sensor, in question, on bank 2 and no activity on with the good sensor on bank 1.

 

I was using this diagram for wire colors....But it doesn't show me where to look on the ecu connector.....even if I were to solder in a new piece of wire.

 

I thought about it and I have not checked the voltage as it was running. Only with the key to the on position. It is hard to get to the splice I made when that manifold is hot. Does anyone know which wire and location of said wire to test for return voltage at the ECU/ECU connector?

 

You have a scanner right? Does it have live data? If so, just check the O2 voltage on the scanner. If it's reporting anything other than zero volts then the signal is making it to the ecu and you have an O2 or heater wiring issue. The unresponsive O2 code tells me that the sensor is probably vaulty but you can easily rule it out wit the live data.

use one at an auto parts store if yours doesn't have live data.

 

When I turn the key to the on position, everything lights up. Every sensor has ~.445 depending on temperature. When I start the truck, all o2's move normally except the bank 1 sensor 1, which hovers at .450. I have a Autel scan tool and actron. both scan tool produced the same data.

 

When you are driving does the sensor in question ever start fluctuating? If the heater is bad It will take a long time for the voltage to start swinging and only way to get it hot enough is to drive down the road.

But I digress, if the ecu is reporting voltage then it is getting a signal.

​​​​​​I have a hard time following your first post. Have you swapped the sensors back and forth yet?

 

Yes. I have swapped the o2 sensors. It works fine on the other side. I also bought another one and swapped it in as well, just in case. It works as well.