Quick o2 weirdness question/validation
 

My disco has 135K miles, so it is overdue for the o2 sensors. Everything has been fine - no codes - but my mileage could be better. Replaced them last weekend.

Started getting p0150/p0130 codes yesterday. Hook up the scanner, and I'm getting 0 volts on both of the upstream sensors. Disconnected the passenger side one to test things, and I am now getting data for both (!?) upstream sensors (despite the fact one is disconnected).

From what I have read, its normal for a disconnected o2 to pick up stray voltage, so that is not so weird. Having one sensor 0 the output of both sensors seems a little strange.

I am 80% sure I got a bad o2. Anyone want to reassure me?

-rj

Uncle D,

Where did you get your O2 sensors and what brand did you get? I've read a lot of posts on this forum where people went thru a few to get a full set that worked. If I recall it right, people seem to think that the Bosch sensors were the way to go. Better quality & such.

Theory #2 I had a bad one replaced by a great local indy shop about six months ago (passenger side pre-cat one) and they said the electrical connectors were a weak spot. Especially when oil leaks onto them. They said that even if you plug in a new one it will short out/go bad very shortly. And that the front two are in locations that get typical rover oil leaks.

So long story short, they clipped the connectors off, hard wired them together and sealed them up with some shrink wrap and I haven't had an issue since.

Hard wiring them was a new take on things for me so I just thought I'd pass that along.

Kinda reassuring? Maybe? :D

What brand? Last year I bought 4 bosch front sensors. 2 failed, returned and replaced and now 1 is failing again. Im not sure if its the sensor or some weird electrical stuff. Thats why i purchased them now on local autozone or advance. Easy to return. But before that, i got the replacement from Ab which never had any issues for a very long time. They look generic though.

I read the same things - everyone said Bosch, but everyone was also finding bad sensors out of the box. I went with some generic ones off ebay that seen to be a pretty nice quality from a wire and connector standpoint. They look like NTK, but who knows. Time will tell, I'm sure.

I wouldn't be surprised if the connector was sketchy. Between the heat cycles, oil soakings, and eggshell-fragile land rover plastic, I should be happy they are even there at all. I've had to direct wire the ABS sensors already. There is so little clearance to solder there I'm going to cross my fingers and hope a new sensor does the trick. I'll update the thread for posterity-

-rj

IF you bought Bosch from Amazon there is a very distinct possibility they are bad. I had one bad right out of the box, then two go bad inside six months, then a fourth go bad. All Bosch all from amazon. I went with Walker from AB.
Land Rover Oxygen Sensor Replacement (Same Fit As Part # 250-24496)

Doug told me that these are what LR folks use as replacements in the UK. So far so good.

Okay, got my Bosch from amazon today (yikes), and I have a question. What readings are good? At this point, the new one reads 0.00 much of the time, occasionally going to 0.05 or 0.1. The other upstream one is more constantly in the .07 range, never hitting 0.00. The rears hover around .45 with some slight variation that let me know they are at least changing. Normal?

-rj

update - I drive for 15 minutes. now the new is on 0.0 all the time, other upstream one is in the .7 range, and the rears a little higher than the front. I'm going to double check the wiring, then send it back to Amazon. Argh!

Clean and check the connections before you take them out again. Do not use dielectric grease on the actual connection. It is meant for the outside to repel water.
It sounds a lot like you are going thru what I did with AMZN sensors a while back.

It certainly does. It looks like the sensor reads .455 along with all of them cold, but as it warms up it zeros out. On the happy note, it doesn't make the other upstream sensor zero out, which I assume was some sort of short.

At least Amazon has free one day shipping.... this is getting old quickly tho. All the local parts places have Bosch sensors. Is there something magical about Amazon, or are all Bosch o2 sensors a roll of the dice?

-rj

Oh man...I ordered the Okay Motor brand from Amazon:

Amazon: Upstream O2 Oxygen Sensor for 1999-2004 Land Rover Discovery 4.0L 4.6L Part #: 234-4694, MHK100920, SU5577 $30.00

Was going to give it a try this weekend