raphael46 0 Posted June 15, 2006 Report Share Posted June 15, 2006 My 96 OBD11 VR6 unmodified (apart from a panel air filter anyway) Golf has just failed the MOT on emissions. The CO reading on idle was massive - 5.7 or so. Put it on Vagcom and there's a fault code - "O2 sensor short to ground" Seems obvious enough, the O2 sensor is duff, but it was only replaced a few weeks ago, with the correct Bosch one, following the discovery on Vagcom that the original was produscing no signal at all. The replacement seemed to be working fine at the time.Emissions test at 2500 rpm (or whatever the MOT calls for) is perfectly OK and, of course, it drives happilyO2 sensor output voltage at idle on Vagcom is around .4v to .45v Open the throttle a bit and goodbye voltage, it seemingly drops immediately to 0v. Close throttle and back to .45v ish. Beginning to wish I had my own gas analyser and an ocilloscope now!I'm intending to check the signal voltage at the connector in the engine bay at some point. Would have done it tonight but I managed to pull the probe off the end of the +ve lead of the meter trying not to burn myself on the exhaust manifold (again)Any ideas/suggestions? I guess I could try another sensor but I'm loathe to spend another £65 at this point. I was wondering about a duff ECU but everything else seems perfectly OK. Help! Link to post Share on other sites
riggs 0 Posted June 15, 2006 Report Share Posted June 15, 2006 Shit ! got the same fault code for my 96 also mate and my MOT is tomorrow Link to post Share on other sites
raphael46 0 Posted June 16, 2006 Author Report Share Posted June 16, 2006 OK, OK, I can't stand it any longer. How did your MOT go? Link to post Share on other sites
riggs 0 Posted June 16, 2006 Report Share Posted June 16, 2006 OK' date=' OK, I can't stand it any longer. How did your MOT go?[/quote']Emissions fail !! lol Link to post Share on other sites
raphael46 0 Posted June 16, 2006 Author Report Share Posted June 16, 2006 And any clues as to what needs sorting? Quote from my tame and normally very helpful mechanic: "Hmmm. That could take three days to track down" Link to post Share on other sites
riggs 0 Posted June 17, 2006 Report Share Posted June 17, 2006 Think mine is just the Lambda sensor (hopefully) the tit that fitted the exhaust was like something from the hills have eyes! lmao Link to post Share on other sites
fredfelcher 0 Posted June 18, 2006 Report Share Posted June 18, 2006 Not an expert, but it sounds more like a wiring or plug fault to me. It's unlikely that the new sensor would be faulty (although not impossible) - especially if it's from Bosch.You can't really get a good reading from the sensor with a voltmeter; it switches between about 0.1V and 1V a number of times a second - so even a digital voltmeter will tend to just show an average. You really do need an oscilloscope to check it - sorry!Perhaps you could check the wiring between battery earth and the connectors in the plug and see if you can find where the power gets lost - maybe the wiring has cracked inside the insulation somewhere. Not going to be much fun - hence the gloomy prognosis from the mechanic!Good luck though, hope you get it sorted. Link to post Share on other sites
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