i used a 17mm line wrench, worked perfect, didnt have any clearance issues. Already had it and it was all i needed (thank god)

 

So I just bought a 97 disco I and the "check engine" light is on. I had Autozone pull the codes and it looks to be O2 sensors. I did the research and I purchased 2 ea. Bosch 13021 because it appeared they are equivalent. I just pulled the service manual today and it turns out my disco has 4 ea. So........

• Should I replace all 4?
• Replace 2 (which i already purchased)
• or what would you do?
• Can I plug them in without installing them to see if the light goes out to isolate the fault?

Any advice would be great.

 

One: the light does not go out by itself, you have to slear it with an ODB code reader.

Two: the front ones determine the input by the ECM, they are the important ones. The rear ones only turn on the light to let you know the cats are bad. Don't need to worry about them now.

They are a real bitch to reach, Have fun.

 

My light reset itself. Just be patient. It only took like a day and maybe 3-4 starts to clear. Yeah x2what Danny said. The backs are pointless especially to replace at even 50/sensor on the cheap side. Leave em be.

 

So to answer your last question...no. That won't clear until the ECM starts receiving good signals about your air fuel mix from the o2s which won't happen until they're installed.

 

I am surprised to hear that. I am under the impression it has to be cleared with a code reader on the 97 at least. I may be laboring under a misconception or misconstruance or i may just be wrong, I am not sure.

Live Learn Love Leave

 

Yeah. Autozone won't clear codes anymore. So I was getting all geared up to do a negative terminal disconnect and the next time I got in the truck ('99) whammo. No light. I guess the ECM got what it wanted from the o2s and decided to play nice.

 

The Advance Auto stores here are pretty good about letting me use the code reader myself, they just want the driver's license to hold. One of their locations is different, they insist upon doing it so you do not damage their code reader. I went there, the kid doing it could not get it to work. I think he selected the wrong set-up. He was a jerk, he almost broke my ignition key. I had to order him out of my Disco and then he was even worse.

He insisted the problem was not him or the code reader but my screwed up connector. I went to their other location and was able to do it just fine myself.

I did see AB has a code reader on special for 100 bucks that even does live data.

Also saw O2 wrenches at Harbor Freight for under 10 bucks, but not sure about the size (17mm is what we need). My son had gone to NAPA, Sears, Pep Boys and Advance Auto with one of my sensors in hand, none of them could fit it, some said they cannot even order it, some claimed there is not even one made that size. You know how some of those places can be.

 

Just buy a set of metric line wrenches. They work perfect and you should have em in your box anyway.

 

A soft code can clear itself. But hard codes must be reset by means of a code reader. Not sure though which codes LR considers hard or soft.