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I've been looking through the form but still need some guidance diagnosing an issue I'm having with my 2000 Discovery II.
The Problem - Check engine light is on and throwing the following codes (preventing me from passing emissions and registering my rover ):
P0134 - $12 - O2 Sensor Circuit No Activity Detected Bank 1 Sensor 1 P0154 - $12 - O2 Sensor Circuit No Activity Detected Bank 2 Sensor 1 P0135 - $12 - O2 Sensor Heater Circuit Bank 1 Sensor 1 P0155 - $12 - O2 Sensor Heater Circuit Bank 2 Sensor 1 P0141 - $12 - O2 Sensor Heater Circuit Bank 1 Sensor 2 P0161 - $12 - O2 Sensor Heater Circuit Bank 2 Sensor 2 P0140 - $12 - O2 Sensor Circuit No Activity Detected Bank 1 Sensor 2 P0160 - $12 - O2 Sensor Circuit No Activity Detected Bank 2 Sensor 2 p0440 - $12 Evaporative Emission System < this is new after driving it for about 5 miles
What I've Done
Replaced all 02 sensors with Bosch Exact Fit Oxygen Sensor 15630 and 15175
Results so far After replacing the o2 sensors the error codes come back within a mile of driving.
At first, live monitor showed all o2 sensors reading 0.450 with no change as I drove. When I took them on a longer drive I started seeing some changes in the reading going up to 590 etc.
Recent Repairs (the above o2 sensor issues were already present prior to repairs): I recently replaced the head gasket, new spark plugs and cables, new water pump, new radiator hosing, new belts, timing chain and timing chain cover. The above problem was present before these repairs but I waited till after I completed them to install the new o2 sensors.
Thoughts on what it could be:
Based on what I've read on the forum here are a few things I think it could be, but don't know for sure.
1. Wiring harness
2. PCM - power train control module failure (would this mean new ECU?)
3. Bad ground somewhere (haven't been able to find one that is disconnected)
Goals & Thanks
I love this rover and want to have it winter ready by the end of September. The o2 sensor issue and now the 0440 code mean I can't drive it or register it.
Any thoughts on next steps or approach to solving this would be greatly appreciated. And thank you to everyone on here for all your great advice!
Had a guy bring his 2000 Rover over last week to put a window regulator in and while I was at it i read his engine codes
and he had the same Sensor codes so I took a look and he had new 02 sensors installed except whoever installed them put the
rear sensors in the front and the front sensors in the rear, OMG his exhaust reeked. Just take a look to see if you have orange to orange
and grey to grey.
Thank you for the heads up! I just double checked and everything looks correct - orange to orange and gray to gray.
Not going to lie, I was really hoping I had just made that mistake haha.
Were you getting the same codes before changing all the sensors? The heater circuit is simple positive/negative - you can test that if you have a volt meter. You can also bench test a sensor with a volt meter and a propane torch, look up youtube videos on how to do it. Kinda unlikely you had four bad new sensor, but possible I guess. I did have a ECU where the oxygen sensor drivers went bad, but it was only one driver and it was one of the primaries.
Yes I was getting the same codes prior to changing the sensors. I just tested the o2 sensors heater circuit with a multi-meter / following an youtube tutorial and everything tested okay. Is there another heater circuit I should be testing?
You tested the sensors? So if you tested the sensor heater circuit all you should get is a resistance - forget how much - it is just a resistance heater. With the truck running you should be able to measure voltage at the heater terminals on the wiring harness plug. Also, if you disconnect the front sensors the ecu will put the truck in speed density mode and use the MAF for fueling - you can then check the voltage on your new sensors (with them installed) and you should read somewhere above 1 volt on the sensor leads (not the heater leads). Check the Rave for the wire colors.
Bad fuel possibly?
Check the 15A fuse #F2 in engine bay if it's blown?
Check that all connections are tightly secured to ECU module?
Did you unplug your MAF to see if anything changes when it's running?
Also I've read that the Bosch O2 sensors aren't that great. I prefer NTK brand while other Disco 2 owners like the Walker brand.
Last edited by JUKE179r; Sep 23, 2019 at 07:23 AM.
Thank you both for the leads. Everyone has been super helpful, I hope I can return the favor at some point on here.
I'm out of my depths when it comes to most electrical but am excited to learn.
I'll start working through each of these suggestions this week and report back as soon as I am done!
I'm still here working away on this issue. I checked Fuse 2 and everything was good.
I decided to try replacing the Bosch sensors with some Walkers from Rock Auto.
I thought it was a long shot that all four sensors would be bad but after installing the new sensors I jumped in the car with a live monitor and low and behold I was getting readings that made sense (see attached).
Sadly the check engine light came back on almost immediately after clearing the codes. I've tried deleting the pending codes a few times but they come back within seconds.
Code P0161, P0134, P0154, P0135, P0155, P0141.
From what I can see the new o2 sensors are working, they read what I would expect as I drive (granted I have limited experience with all this).
I'll keep trying out everything suggested here - next step is to get to ECU and check the connections.
Let me know if anything else comes to mind with this update.
I found my F2 fuse keep blowing so that’s why I suggested you check your F2 fuse. I thought it was weird also that all 4 O2 sensors would go bad to include SAI pump, purge valves, MAF sensor, EVAP canister, and camshaft position sensor. I started checking the one item that ties all these system faults together... the ECU.
I followed all the wire connections coming from and going to the ECU and found my negative battery cable being the culprit. It was tightly secured to the battery but when I removed it to closely look at it I found many frayed wires and corrosion inside the instullation.
I made an shorter and thicker negative battery cable at 0AWG and installed it.
For the past 3 days I haven’t had any check engine lights, fault codes or a blown F2 fuse.
Long story but... really check your battery connections. Lol
02 Sensor Troubles
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