JohnA Posted July 11, 2005 Author Share Posted July 11, 2005 ... Is it possible (or even sensible) to try cleaning the o2 sensor before going for a replacement? You could try brake cleaner, sometimes it works if there is excessive carbon buildup (I've never managed to revive a dead O2 sensor, but others have claimed to do so) I'd go for a new sensor though, it's like a battery so it slowly degrades anyway... Quote Link to comment Share on other sites More sharing options...
merckx Posted July 12, 2005 Share Posted July 12, 2005 Here's some interesting reading on O2 sensors, it appears you can test the sensor with a decent multimeter. Never tested one yet, not sure if this would just reveal a non functioning o2 sensor or it can be used to test for one that is giving slightly faulty readings. http://www.unofficialbmw.com/all/engine/all_o2sensor.html Quote Link to comment Share on other sites More sharing options...
JohnA Posted July 12, 2005 Author Share Posted July 12, 2005 You can't *really* measure the sensor, not to an adequate degree of accuracy anyway. You can just verify that it's dead, but that's it. If it is slow and errs towards 'lean', as they do when they're old and tired, it will still register a valid voltage, but it will be lower than what it should have been. The way to test it is to have the output compared to that of another, calibrated sensor. Quote Link to comment Share on other sites More sharing options...
supRo Posted July 12, 2005 Share Posted July 12, 2005 guys, is it hard to change the o2 sensor?? and prices/part numbers would be nice too Hope this isn't a hijack, but... I just found out my odo is running in km not miles, this means I'm getting around 14 mpg lately From what I've seen in this thread it looks like I may have a problem with the o2 sensor being faulty or fouled up. (It was running with a very high fuel pressure for a couple of months and seriously sooted up my old ik24 plugs) Is it possible (or even sensible) to try cleaning the o2 sensor before going for a replacement? Also is the o2 sensor the probe mounted in the exhaust manifold just before the first cat pipe? My fuel economy was stupid. From the experience with my car, I would definitely recommend changing the o2 sensor then checking the Air Fuel Ratio. I love my car even more now that it is MUCH more economical and slightly smoother. I've had my AFR's checked before with the old o2 sensor and the economy was still terrible. You may want to check things like sparkplugs first - if they are dodgy Replacing the sensor is very easy. On my Jap pre-VVTI it's located just below the turbo on the downpipe. Partnumber is (Oxy sensor) T89465-19635. £105.05 +VAT The sensor comes with the lead attached and a new gasket. Note: Partnumber is different to the original that was in there. Maybe it's a revision to the original and better??? New bolts (reccomended) T90179-08059. 79p (2 needed) It may be easier if you take off the first/top Intercooler pipe and air intake pipe off. There are 2 12mm(?) nuts holding it on. Slight pain to get to - bit of soaking in wd40 makes it easier to get them off. There are two push fit studs that clips the lead in place. The one nearest to the turbo is easy to take out - pair of pliers to squeeze the prong. The other one is a bit of a PITA as you can't access the prongs of the studs. You may want to cut out/drill the stud if you want to re-use the hole. Or cut the plastic top bit to release the cable. The end of this cable is push fit fitting which attaches to the lead that goes to the ECU directly I think (??) Just disconnect this, near the actuator/fan. To fit the new sensor, just reverse the process. It's probably worth re-setting the ECU. Have the AFR's checked on a Dyno Quote Link to comment Share on other sites More sharing options...
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