Hi all, two weeks ago i bought my first Land rover, a 1999 Disco2 with 145,000Km on the clock. During the test drive i pulled the codes with my code reader they were as follows:

P0134
P0135
P0154
P0300
P0306
P01668
So i have replaced the plugs(bosch plats), wires and all o2 sensors with Bosch direct fit. I now have more codes: p0134. P0154. P0135. P0155. P0141. P0161. P0160. P0140. Obviously i'm missing something here, any thoughts?
Jon.

 

Did you clean the oil out of both of the front connectors?

 

Yes. Everything is clean.

 

Do you have an OBD2 type scanner that can show live data? Maybe you can watch the o2 activity and see if there is any? I'm wondering if you have a wiring problem somewhere though.

 

My scanner does not show live data. I have thought of a wiring issue but is it likely that all 4 sensors to have the same wiring problem at the same time?

 

Should there be continuity between any of the pins on the harness o2 sensor plugs?

 

You don't want to check for continuity if the harness is still connected to the ECM. If you probe something that isn't designed to handle much current, your meter might fry the computer, probably not but I wouldn't risk it. There should be wires for signal and wires for the heater.

 

I know but thanks for the heads up. So with ecu unplugged there should be no continuity between anything?

 

No. Please open up your free copy of the RAVE, circuits manual, you'll find that pin 3 of each O2 connector is brown with pink, and these are common to each other and switched battery volts along with other sensors. So those will read "continuity" from one harness connector to the other.

The other three pins of each connector run back individually to the ECU connector. Inside the ECU connection may or may not appear depending on state of the ECU and your test device.

Yes, you can damage the ECU with poor handling or wrong application of testing devices.

With ECU plugs disconnected and connectors for the O2s apart you should read no short, open, or grounds from the ECU end of the concector toward the O2. With an extra long home made meter lead you can read each pin on the cable to the other end of the cable for continuity. Pin 3 does not go to the ECU, it goes to that common plus voltage connection when the ignition key is turned.

So for the O2s to work, battery volts must appear on pin 3 of their connectors. When key is turned. Check fuse 2 in the underhood compartment.

 

Thanks Buzz useful info. All fuses are good. Just bought a new scanner which shows me that all o2s are cycling up and down with throttle input. Bear in mind that the tool is new to me and I'm new to all this electro mumbo jumbo. What would be the correct cycling of the o2s?

I have not tested any wires yet but will get to it.
Thanks for all of your help so far. Jon.