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Audi TT 1.8 2002 - 5 wire Lambda sensor - Fixed #

Posted by Pete Mutlow on December 29, 2009, 11:56 am

Year of Manufacture *: 2002
Engine Code or CC *: 1800cc
( Optional ) Scanner Used: ACR4 G2

Greetings and Salutations to all,

I am currently investigating why this thing has failed the MOT Emission Test. To complete my diagnostics, I am trying to find out how the 5 wire Lambda sensor works. I have trawled various sites and forums and have found nothing of interest so far.....The voltages are completely different to the conventional sensors and I need some info/traces etc to condemn if necessary this aftermarket Lambda Sensor which was fitted to get it through the MOT.

Any info or a point in the right direction would be much appreciated.

Prosperous and Happy New Year to all

Pete M

Re: Audi TT - 5 wire Lambda Sensor

Posted by Mark Storey <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5564' width='330' height='300' border=0 style='border:none;'> on December 29, 2009, 1:59 pm, in reply to "Audi TT - 5 wire Lambda Sensor"

Hi Pete,

I assume that this is a broadband sensor?
Best place to start is to read the Toyota training information on Iatn. (A couple of hours reading for you)

.
Hth
Mark

Link: http://members.iatn.net/resources/toyota/sensor/sens_16.html

Re: Audi TT - 5 wire Lambda Sensor

Posted by Aidan Birley on December 29, 2009, 2:04 pm, in reply to "Audi TT - 5 wire Lambda Sensor"
Message modified by board administrator December 31, 2009, 11:17 am

pete

Try web search using wide band lambda sensors this may help.

These are pretty good at showing fault codes if faulty, have you any codes logged ?

What make was the after market sensor ? genuine from TPS are not that expensive.

Would be good to post 4 gas and live data if you need more help with fault.

Cheers Aidan

Re: Audi TT - 5 wire Lambda Sensor

Posted by craig davies <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1582' width='330' height='300' border=0 style='border:none;'> on December 29, 2009, 10:20 pm, in reply to "Audi TT - 5 wire Lambda Sensor"
Craig Davies

hi Pete don't know if you have seen the video on pico site does not really explain how they work but does give a test for them.
http://www.picoauto.com/automotive-oscilloscope-guide/lambda-sensors.html

Re: Audi TT 1.8 2002 - 5 wire Lambda sensor #

Posted by Philip Cockburn <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2627' width='330' height='300' border=0 style='border:none;'> on January 4, 2010, 10:23 pm, in reply to "Audi TT 1.8 2002 - 5 wire Lambda sensor #"
Philip Cockburn

Hi Pete
A couple of thoughts here, is the sensor the correct one for the car? we are very suspicious of aftermarket sensors nowadays, if it is Bosch or NTK & correct fittment should be ok though.

When testing these you can follow the Pico video which will give you an accurate footprint of fuel control (remember reverse/upside down though!!) or you may also be able to read the serial data through your scanner?? if it supports this? possibly via EODB
Autodiagnos does this on some applications & shows the sensor current change (very small MA just above & below zero MA as the system switches in closed loop).
If the sensor is locked + or - you could use a gas bench to confirm findings, this should also co-relate to serial data for fuel trim.

Regards Philip

Re: Audi TT 1.8 2002 - 5 wire Lambda sensor #

Posted by Anand Dattani <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3015' width='330' height='300' border=0 style='border:none;'> on January 7, 2010, 3:58 pm, in reply to "Audi TT 1.8 2002 - 5 wire Lambda sensor #"
Anand Dattani

Hi Pete

Just looked at a wire diagram of the TT and it shows a standard 4 wire sensor. If this one has a broadband sensor you willneed to trust your scanner because from what i have understood it is very difficult to test a broadband lambda sensor even with a pico unless there is no signal.

good luck

Anand

Re: Audi TT 1.8 2002 - 5 wire Lambda sensor #

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on January 7, 2010, 7:21 pm, in reply to "Re: Audi TT 1.8 2002 - 5 wire Lambda sensor #"
Peter Mutlow

Evening all,

This is an interim response out of courtesy to you guys who have given their thoughts to this. I am not seeking further help at the moment.

The Lambda sensor is a 5 wire item from main dealers. I am now happy that this thing is working OK. On my last visit, I got fault code PO171 (Lean mixture) for the first time. As this can be associated with the Air Mass Meter, I looked at this again and found that it was not 100%. Scoped image was not brilliant and found at idle I had 1.1v (should be 1.5v) and peaked at 3.8v. So another one will be fitted soon.

The other thing which I noticed as interesting was that the mixture at idle (1.6%) would come good when I cleared the Fault Code and then in about 10secs rise to its original value. Ditto fast idle rising back to 0.8%. This would happen when there is no fault code present and I pressed the reset button on ACR4 G2. LTFT is 25%.

I was interested in the cost of these original items. Lambda Sensor at £112 and Mass Air flow Meter priced at £92. Main Dealers are now getting the message.

Will provide feed-back when available.

Regards

Pete M

Re: Audi TT 1.8 2002 - 5 wire Lambda sensor #

Posted by Simon Dean <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5221' width='330' height='300' border=0 style='border:none;'> on January 9, 2010, 6:07 pm, in reply to "Re: Audi TT 1.8 2002 - 5 wire Lambda sensor #"
Simon Dean

Hi pete

You can monitor the 5 wire sensor on the pink wire.
This is not control but transitional voltage and you should get a reading of 2.5v to 3v for a vehicle that is fueling correctly.
It is opposite as said previously...low volts signal defficiency of oxygen....high volts signal excess oxygen.
You could monitor rear zirconia sensor for reaction times together.

HTH
Simon

Re: Audi TT - 5 wire Lambda Sensor

Posted by kevin sellars <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1895' width='330' height='300' border=0 style='border:none;'> on January 10, 2010, 10:20 am, in reply to "Re: Audi TT - 5 wire Lambda Sensor"
Kevin Sellars

hi, a faulty pcv valve will cause lean running codes and will also set high fuel trims, you can usually check by pulling off oil filler cap, if its faulty there will be suction.( at idle ). cheers kev.

Fixed #

Posted by Pete Mutlow on January 11, 2010, 10:57 am, in reply to "Re: Audi TT 1.8 2002 - 5 wire Lambda sensor #"
Message modified by board administrator January 11, 2010, 2:44 pm

Morning,

Air Mass Meter from Main Dealers fixed this.

Many thanks to those who contributed.

Regards

Pete M

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