QuestionJohn:
My check engine light came on today though I do not hear, feel, or see any problem. I have been told it is probably the oxygen sensor since it has 89,500 miles on it. (It's a 2000 Disco II).
The dealer wants $100 just to tell me what the problem is. I would rather spend that money on fixing it myself. From what I can see, there are two sensors before the Catalyst in the exhaust manifolds. Are there two sensors or four? I was told there might be four of them. Should they be replaced in pairs, even if only one is causing the problem?
If I do this myself, what is the procedure to resetting the light?
The only service I know about or have had accomplished are normal oil changes and tire rotations. I did replace the brakes/rotors about 8 months ago.
If I have to buy a engine code reader, what is it called and approximately how easy are they to operate?
Much regards,
M Nance
AnswerHi Michael,
most auto shops have OBDII readers at reasonable prices. Advance Auto has good prices and they'll even read and reset the code for you...if you ask... FOR FREE! They can show you where to connect the reader and its not that complicated to operate. Your Disco II is more sophisticated than my series I and a good OBDII reader/scanner would be very useful. Some simply read the code, others can run diagnostics in real-time mode. Some are $50, others are $500.
Your 2000 Disco Series II could have four O2 sensors, two in front of the catalytic converters and 2 after the cats. If you look up under the Disco and see O2 sensors just after the cats, you probably have two more in the engine compartment just after the exhaust manifold on the "Y" pipe.
As far as I know, you don't have to replace them in pairs but don't forget to use anti-seize compound when you do replace them. If you can find an O2 sensor socket or wrench, buy it. I don't have one but I wish I did. It looks like a box wrench but the "C" is closed more to prevent slippage.
If you do replace the 02 sensors, disconnect the negative cable from your battery. When you finish your install, reconnect the cable. By removing and reconnecting the negative cable (for a few seconds) it usually wipes out any OBDII codes that have been trapped by the system.
Here is an article that might be of interest to you. It does not talk about your specific engine management system BUT it describes how O2 sensors function and what to look for in diagnosing O2 problems:
http://www.roversnorth.com/LRinfomenu.html
download the PDF file from Tech info: Summer 2005. Excellent article for '95 Disco. Your 2000 Disco is very different BUT the article talks about O2 sensors and how some owners are tricked into thinking the O2's are at fault. Interesting read.
Lastly, I'd suggest you go to the BOSCH website and search for O2 articles. I'm not sure if BOSCH still posts them but if you want to save time, send me an email and I'll forward you the two PDF articles I have:
O2 sensor installation; how to recognize a bad O2 sensors.
jmcinnis64@hotmail.com
Best of luck,
JohnMc
