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VW Golf 2.0 AQY 2001 - MIL on intermittently #

Posted by Dave Wolveridge on August 13, 2010, 5:54 pm

Year of Manufacture *: 2001
Engine Size and Code *: 2.0 AQY
( Optional ) Scanner Used: KTS
( Optional) Fault Codes: AC40 Bank 1 mixture too rich

AC40 only fault code stored. KTS reads lambda
control and lambda heater not active. Have checked voltages at lambda and all appear to be correct. Lambda is switching at correct rate. Once engine is warm, mixture adaption is reading 16 - 18%. I have checked ignition system, exhaust emissions are fine, car starts and drives with no problems.I have checked condition of catalytic converter and have checked related items as per ESI, have actually replaced lambda probe and injectors. We are thinking a possible ECU fault, running out of ideas, any help would be much appreciated!
Dave

Re: vw golf Engine Management Light Intermittently On

Posted by Sam Green on August 13, 2010, 9:46 pm, in reply to "vw golf Engine Management Light Intermittently On"
Message modified by board administrator August 16, 2010, 8:06 am

Hello dave. I take it that you meen plus 16-18 on adaptions. Sounds like you have an air leak, check EVAP or breather system. Smoke machine would be a good idie if you have one. Hope that helps!!
Sam

Re: vw golf Engine Management Light Intermittently On

Posted by Matt Booth <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3028' width='330' height='300' border=0 style='border:none;'> on August 14, 2010, 5:16 pm, in reply to "vw golf Engine Management Light Intermittently On"
Matthew Booth

Rare for the ECUs to fail on these. Take a look at the following like for ideas.

http://wiki.ross-tech.com/wiki/index.php/16556/P0172

What voltage are you getting from post cat probe? Have you tested the maf? Have you checked fuel pressure?

Matt

Re: vw golf Engine Management Light Intermittently On

Posted by Mark Carter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on August 14, 2010, 11:04 pm, in reply to "Re: vw golf Engine Management Light Intermittently On"
Mark Carter

Hi Dave, Hows life?
If the ECU is reporting that the system is too rich, then you need to sit down and make a list of all the things that could cause that to happen, then look at the list and work out how you can test for each item on it. Don't forget live data as a diagnostic tool. HTH

Regards Mark

Modern cars, Its all wizardry and witchcraft

Re: vw golf Engine Management Light Intermittently On

Posted by John Ritchie <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2638' width='330' height='300' border=0 style='border:none;'> on August 15, 2010, 2:15 pm, in reply to "Re: vw golf Engine Management Light Intermittently On"
John Ritchie

Hi Dave , what are your gas readings ? , any history on the car like timing belt replacement etc? , fuel pressure good ?

Regards
JR

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