should i buy new o2 sensors for the mechanic or let him get them?

[aharbour]

Hi all.
My 1997 disco is giving a P0158 code. It translates to an O2 sensor error.
These are the 3rd set i will have gone through in its 11 years.

I spoke to the mechanic that does work for me and he said that they are expensive, in the $300 range. I know they are much cheaper, but if i buy them
myself is it possible to get the wrong ones - i am a little worried that some seem to have a heater and some dont etc. The first time i did it was at land rover for over $1000 (never again)

Is it possible the error code is from something else or will replacing them fix the code?

Do i need all 4, front 2 or back 2 or just one?

[tyl604]

Disco Mike will give you the real scoop but here is what I know. You will save money buying yourself. When you order the sensors, make sure you give them your VIN and ask if you are purchasing the proper sensor for that vehicle and VIN.

I paid $65 each for Bosch sensors from warehouseautoparts.com (that might not be exactly the name but it is close). First I bought a Bosch ($65) and ARBL ($45) after going through their parts section and ordering myself. Turns out that the ARBL was not made for my 99 Disco II (found that out by talking to a real live person at warehouseautoparts.com a week later after my codes came back on) even though the website said it would work. So I went to two Bosch sensors.

From talking to Disco Mike I think he recommends you use the same brand all around. He also feels we should stay away from really cheap ones. But that's about all I know and my codes are still on.

[osiristheclown]

You can replace the 2 front ones as a set, they control mixture. The 2 rear ones are there to tell the ECU that the catalytic converters are working correctly. I put 2 new ones up front and put the good used ones behind the cats. Shop around on the web, you can get the sensors for about $100-$120 each for NGK/NTK brand. I think Summit had them last I looked. The plug will determine which sensors fit your truck, many of the Rover parts places show pics to help identify the correct ones for the application. Do not bother with universal sensors. There is no reason you can't change the sensors yourself and erase the codes.

[tyl604]

Oclown - not sure what you mean about good used ones? The front and back sensors are not interchangeable (at least on the Disco II). Did you have some good back sensors that you just left in? This could be since the codes tell exactly which sensors are not performing correctly.

Agree, they are easy to replace. Buy a crow's foot socket - $10 at Pep Boys. Makes it a lot easier to remove. Spray each sensor with WD40 the night before and let the threads soak.

Note about original post - your codes will tell you how many sensors must be replaced. I think Disco Mike's theory is that it makes sense to replace all four while you are at it.

[osiristheclown]

My truck uses the same sensor in all 4 locations. ERR1834 is the number for my sensors. I put new up front and used my good ones behind the cats to keep the CEL off. BPU has sensors for $105.

The code may not be telling you the sensor is bad. I had code 1193 which is a downstream sensor and the sensor was good, the cat was bad. I replaced the 2 front sensors with new and put the old front ones behind new cats.

[tyl604]

Interesting. Did not know that the DI had interchangeable sensors. Never had to change them when I had the DI. DII is a different story.

[osiristheclown]

DII sensors are cheaper than DI sensors. DI uses 2 sensors for Lucas trucks and 4 sensors for the GEMS system. DI uses different sensors for AEL and non AEL trucks. My understanding is the GEMS trucks use a Titania element in the sensor while most oxygen sensors use Zirconia. I don't know about the Bosch system, but the GEMS uses the rear sensors to read catalyst efficiency.

[aharbour]

i ready thaty o2 sensors are hard to replace often requiring a blow torch on them to remover them - is that true?

If i but them myself are there different parts i have to buy or just one using for each side up front - if i buy them i want to make sure i have bought the entire component

[osiristheclown]

The sensors are a complete unit, buy the ones for the application and you will have what you need for parts. It was already suggested to purchase a crows foot, this is like a flare nut wrench in that it goes most of the way around the sensor to get maximum grip. They are only hard to change if you intend to reinstall them, you could just chop the wires off the old ones and use a box wrench or deep socket. The ones on my truck were 17MM, and they came out easy using an open end wrench that fit snug. You could use a small pipe wrench if you don't care about the old sensors. When you install the new ones do not touch the end of the sensor, and don't tighten it down crazy tight.