Oxygen Sensors

[Crs]

According to my code reader, I have an error on one of my O2 sensors.
Vehicle: 1997 Discovery Series 1, 4.0L V8 EFI, automatic, 200K miles, US spec SE7
Error Code: P0130 O2 Sensor Circuit, Bank 1, Sensor 1

1. Car running nicely. Do I fix this or live with the 'Check Engine' Light?
2. Replace the sensor, or replace all four sensors as some websites suggest? (I only get the one error code.)
3. Buying a new sensor: I've seen some very low prices on eBay, non-name from the US at about $60, and Bosch sensors in the $130-200 range. Does it matter? This isn't a concourse, all OEM car, but I don't want c**p that will break and need replacing. Suggestions on where to buy?
4. Anyone in the South Surrey/White Rock area have a 17mm wrench (open end) that I can borrow to get this thing off? (My toolbox only goes to 15mm in open.)

Thanks! :D

[ANDYD]

Hey Craig,

Have you tried unplugging the wires to the sensor to see if it changes anything?
After that, try just removing the sensor and cleaning it up, pop it back in to see if that makes a difference.

I have a 17mm wrench is you need it,

Cheers,
Andy

[Hectorious]

I'm resurrecting this thread. I've got the same problem on the same model and year Discovery. Can these O2 sensors be cleaned (and if so, how), or is it necessary to replace them?

Craig, how did you deal with this, and how did you make out? Any others with advice?

Chris

[ANDYD]

I have cleaned mine a few times, it normally clears the code (at least for a few months) How successful the cleaning is depends on whats causing it to get clooged up in the first place. As for what to clean it with, that depends on what they look like when you remove them. If its just exhaust slime you can just wipe it off with a rag, if its hard carbon deposits you may need to use something stronger (i used petrol on a rag). If you have had some head gasket issues they can get really dirty, even quite badly corroded if you have some coolant getting into the exhaust system. No harm in trying to clean them first, cheap fix if it works.

If it doesnt work then they will be easier to get out again for replacment.

I expect Craig will answer the rest of the question regarding buying new ones .......

[Crs]

Hectorious emailed me. I'm posting my response below in case anyone else is in need.

I did the work under close supervision of a mechanic. One upstream O2 sensor was poor and needed to be replaced. Mechanic recommended genuine LR part which was about $300. Access isn't great for the plug, but I managed it. Actual sensor is a little easier than the wiring to get at. You need to look at the new sensor to figure out how to unplug the old one. Then you will find (or I did) that this will require more fingers than 1) will fit, 2) a normal person has. :mrgreen:

Anyway, one new O2 sensor solved the problem. The other upstream O2 sensor had a much slower reaction time than the new one, but it must still be within spec as it didn't throw a code. I had to use my code reader to cancel the error code after replacing the sensor.

How to do it? I googled it and have the Service Manual. However, I've found the Service Manual tends to skip steps that it assumes mechanics already know. I'd like it to be more precise (e.g. Step #1: find you tool box...) Google was good on the steps and helping me locate the O2 sensor. I ended up phoning the Richmond JLR service department to ask which side was 'bank 1' and which was 'bank 2.'

If you're not sure that the sensor is the issue, try to borrow a sensor. If a known good sensor solves the problem, it's the sensor. If the error comes back, then it's something else. (And sorry, as mine was the sensor, I have NO idea what the 'something else could be.)

Mechanic told me that the upstream sensors are quite important and MUST be kept in good condition. Otherwise the engine will run out of tune and cause you further problems down the road. A warning from a downstream O2 sensor (e.g. after the catalytic converter) only tells you about the health of the cat (or the sensor). Downstream errors won't affect the running of the engine, just the emissions.

BTW I was loaned a sensor from a slightly older Disco (a 95 or 96) and it used a DIFFERENT SENSOR. They seemed to change a lot around that time and the same model year can have more than one. If you buy from a JLR dealer or LR parts specialist, give them the VIN and make sure you get the right one. Also, once you get the old one out, check that they look the same before attempting installation. I can't remember now, but I think the actual sensor is quite delicate.

BTW #2: It's on the exhaust system, so it will all be insanely hot if you just drove the car. I'd give it a L O N G time to cool down as you have to get quite up close and personal trying to unplug/plug in the sensor.

Good luck. Any other questions, drop me a line and I'll TRY to answer. However, I'm no expert at this!

Cheers!

[Hectorious]

Thanks so much for your detailed reply - I appreciate you taking the time. I'll crawl underneath and see what I can find.

Curiously, the PO was running the truck on regular gas and reported having no problems. I've switched to Premium and the error light is now only intermittent. Still, I want to get it fixed.
Thanks again for your help. I'll post to the forum how it turns out.

Chris