GolfGTIforum.co.uk
Model specific boards => Golf mk3 => Topic started by: Jasikasisback on 31 May 2013, 14:52
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As my MOT is coming up I want to take a look at the lambda sensor. Is is easy to remove and inspect and then put back without damaging anything? Just wondering as it looks like it is in there quite solid..Reallly I just want to look at it to make sure it isn't all black and clogged and just want to clean it...or is it best to leave it well enough alone...
Any help would be greatly appreciated.
Also what do you guys think about stuff like K-Seal etc....as preventative medicine? (just to avoid having a leak in the future...)
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From my experience, old lambda sensors never come out easily without the application of a fair amount of heat. Even then sometimes they can still kill the threads on the sensor. If its not broken then I wouldn't touch it. Also with K-seal, if you have no problems then you don't need it. No harm in keeping some in your boot for an emergency.
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i'll leave it for now...:)
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just read measurement blocks with vcds and see if it works.
or read output with a multimeter or oscilloscope if you have one, no need to take it out for functional check
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i've got a multimeter. what values am i looking for (cold-hot?) dunno even where to begin. got a link or pics to a guide??
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black = signal for ecu
white = 2 x supply voltage for heating
grey (if present) = gnd
measure voltage between the 2 whites, when engine cold this should be near 12V
black to GND should be fluctuating between 0 and 1V - maybe 1 to 2V if it's a newer type with gnd offset (for open loop detection) but don't think that type was used on mk3s
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i've got a plug with a yellow, white, white with a red stripe and orange/brown wire. Am I looking at the wrong plug? I put 2 pics up on flickr.com
account is vwgolfcl1996.
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ah you've still got an original vw one then... :)
the 'signal' on those is between white and yellow.
heating is white/red and brown wire.
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do i have to have the ignition on for this test?or the car running? i get no reading on the voltmeter
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wires-number 1 on the plug is the red/white pinstripe. number 2 is brown. number 3 is white and number 4 is yellow. i tried 1 and 2 and got no voltage going through it. i've read thet the test has to be done withthe car warmed up at least 10 min so the sensor is functional. I am a total boob when it comes to electronics. i need dummy instructions to do this right...:(.
Found this on another site...
earth brown/black
heater supply red/white
heater earth white
signal wire yellow
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the colours for original vw i got straight from vw software....
should be correct
of course engine needs to be running, how else would the sensor work? should work quite quickly after starting... 10 minutes - in lapland in winter maybe ;) in current weather after a mile it will be already (near enough) operational temp.
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I apologise for being so dumb. Anyway I don't want to damage any of the wires by exposing them or remove the O2 sensor (if I don't have to). The only test I have figured out that I can do is the following:
1. Unplug the sensor as I will probably burn myself trying to get it off once the car is running and hot. Tie the sensor to the fuel lines with tie so it wont be damaged and I can easily access the exposed pins.
2. Drive around for about 10 min or so to warm up the O2 sensor to operating temperature.
3. Take the multimeter and attach the black probe to the car as to act as the ground. Attach the red to the signal wire pin on the sensor plug which is yellow or white (depending on the plug I guess-wont hurt to try either anyway) This will give me some sort of value between 0-1.0V I hope.
4. Rev the car and see if the voltage fluctuates. As I rev it by pulling the throttle cable the voltage should go up and then go down after I stop revving. (inversely mirroring the amount of oxygen available)
In this way I don't have to remove anything and the risk of damaging anything will be minimal. This will at least tell me that the O2 sensor is working? I think I will be able to tell if the O2 sensor is sluggish or not and if the voltage goes up and down then at least it is working for now.
Does that all make sense or am I just spewing rubbish..
Also I could possibly just hook it up to the ground wire in the plug to make sure the ground wire is functioning. (brown?) Maybe best to just ground the multimeter to the car.
Guess I wont really damage the car if I drive for 5-10mins without the O2 sensor on.
I would replace it but as it costs around £60-70 new. It will be hard finding an auto lambda in the scrapyards and as far as I know the AAM engine doesn't really share this sensor with other models/engines..
If this sounds like a good plan then I will give it a go tomorrow.:)
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you can do it the way described. but it could be that the lambda then does not change voltage as the ecu will detect its disconnected and run in rich mode to prevent damage. could be that this is outside of normal operating voltage of the sensor and it will not change value.
will check if there is another point where you could check the voltage from..... maybe easier to get to the pins at ecu?
on ecu its pin 15 (white) and 38 (yellow)
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I've never touched' the ECU. Afraid i Will damage it.:)
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just get vcds (lite) already... ;)
you can check all this kinda stuff in their without mucking about with wiring.
pins at ecu are not too bad to get a hold off.
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yeah you are right.