: o2 sensor---good/bad ?????

first sts
11-20-04, 12:23 PM
When I do an engine reading from the on board computer the Data from the front/rear o2 sensor ONLY goes up to 5,,,,,normal reading is between 0-255 according to ALlDATA.com Does this reading mean that the sensors are BAD oh no!!!
Does anyone know of some place on the WEB to buy them at a fair price if I need them ??????? Thanks

10-06-09, 09:42 AM
:mad: I have a 93 Allante and have been chasing O2 problems myself. Unless your vehicle is a lot different than most cars in the market, a reference voltage of .45 should be what your diagnostics are telling you about both engine O2 sensors when you take those readings with a cold engine turned off. Normal fluctuation with a warm engine running will be very quick, several times a second, and will range from .1 to as high as .9 or so only. If your readings are out of that range, there must be something wrong and I would suspect that that O2 sensor has lost it's mind.

Also, it is never a good idea to change the O2 sensor only on one side of the engine. If you are going to do one, do them both. Those sensors get tired in time and having one new one and one old one isn't doing your vehicle any favors. Since the mid 90's, the recommended change time is about 100,000 miles, but earlier years need changed around 60,000 miles. But let's add just one more factor to the problem. Even if you have low miles on a car and it's been around for 8 or 10 years, I believe that time on the block is enough to justify the sensor change. Other folks may not agree with that, but I think that a car that gets little use is more of a problem than one that gets driven each day, especially highway driving.