O2 Sensors on DII keep going bad...

[roverdriver77]

In the past three months I have replaced two of my O2 sensors (#1 = Pre-catalytic). Admittedly, I have a worsening oil containment problem with my valve covers. I was advised upon replacing the first sensor to tie the connector out of the way so that oil wouldn't drip on it and short it out. This I did. A few weeks after the first was replaced on the right side (= bank 2) the left side (= bank 1) went out. I replaced it and tied it out of the way. Now the left side has gone out again after two months of use. Once they go, I end up in "limp mode" and get about 10 mpg or a little over 200 miles per tank. Gettin expensive... Anyone else have any problems with their sensors going bad. Does a bit of oil on them really mess em up that bad?? I suppose I should probably fix the damn leaky valve covers but I guess I want some confirmation that might help my sensor problems...
2000 Discovery II with a lot of miles...I mean a loooooot!!

 

[brianhoberg]

had similar problems, replaced them all and no more problems.

only suggestion i can offer is that if you ever spray out the engine bay of your engine, be careful about spraying at/near the O2 sensor harnesses as the runoff tends to get in there and you normally have to replace them.

 

[roverdriver77]

I may or may not have sprayed my harness for more than 10 seconds with a 1550 psi power water pressure sprayer recently....
Damn! I think I'll try packing "hi-temp" RTV into the new connectors this time.
Thanks for the response.

 

[KyleT]

use dilectric grease, not rtv...

are you using OEM o2's?

 

[jeffro0502]

Bosch sensors?

 

[BlackAndTan]

Repeated sensor issues here. They're finicky, delicate pains in the ass. I'd do everything I could to keep water, oil, coolant, anything off of them. And stick with very clean fuels etc.

(You don't by any chance have any mysterious coolant issues do you? If so, lemme know.)

 

[Mrmerlin]

pay careful attention to the O2 sensor connectors one of the wires is hollow and this is used as an air path to the sensor, so packing the connector with anything might not be a good idea as you can cut off the air path.
The sensor will then not function correctly.
Similar things happen when universal O2 sensors are used and the wires soldered into place or crimped with connectors

 

[KyleT]

dont put anyhting on the end..... use dielectric grease on the plug....

 

[JohnB]

pay careful attention to the O2 sensor connectors one of the wires is hollow and this is used as an air path to the sensor, so packing the connector with anything might not be a good idea as you can cut off the air path.
The sensor will then not function correctly.
Similar things happen when universal O2 sensors are used and the wires soldered into place or crimped with connectors

Never have seen this. Air tube going to the sensor? That must be the viaduct where the little men carry the sense to the sensors. You know those little men from Tron need to get air somehow.

 

[jeffro0502]

Air path? WTF...

Never have seen this. Air tube going to the sensor? That must be the viaduct where the little men carry the sense to the sensors. You know those little men from Tron need to get air somehow.

 

[rovercanus]

Where do people get this shit?

 

[lforgue8]

very old o2s had a air path for atmosphere readings......like when o2s were first used...........but now days there is perified oxygen inside the sensor for that purpose....

oil contamination can be the problem so fix that oil leak if it that bad and alos dropping a sensor can break the ceramic inside the sesnors as well.........or any shocking to the sensor really....like hammering on the exhaust for some reason

also if you have a looooooooooooot of miles i would do as brain said and replace them all

 

[roverMc]

I kept having the problem of gunk getting into the connections. I cut the plugs off and replaced them with butt connectors. I have no more problems since.

 

[roverdriver77]

Thanks for all the feedback. I am using OEM sensors. So did we decide if there is a hollow duct or not on the new sensors?

 

[roverdriver77]

(You don't by any chance have any mysterious coolant issues do you? If so, lemme know.)

I've had some. The last one was the tiny gasket on the air intake plenum that leaked (actually spurted like an artery). Got that fixed. Occasionally smell coolant but levels have remained constant for quite sometime now.

 

[JohnB]

4 wires thats all. No magic tubes.

 

[lforgue8]

4 wires thats all. No magic tubes.

i thought i had said that

 

[greenrover666]

So if the failure is cause by a contaminated connector plug on the drivers side pre-cat sensor and said sensor failed within 20 miles after using an entire container of brake cleaner to clean the oil out of the connector.

What would be my next best step?

I read where someone cut the connectors and wired them together... this is driving me crazy and I believe this will be my next step. Since this second Bosch O2 sensor is new would it be legit to continue use or return for a new one?

Thanks for any advice.

 

[KyleT]

the ECM can be bad too. i have seen a few that throw primary o2 sensor faults that ended up needing a new ECM.

 

[Blue]

I had leaking valve covers take out one of my O2 sensors too (pre-cat on passenger side). I had the valve cover gaskets replaced and the O2 replaced at the same time.