Question about 1999 Audi A6

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Audi a6 on board computer reading faults

Hi there just wondered if any one no whats wrong with my a6 when starting car abs light comes on and then onboad computer starts flashing no oil and rev counter stops working but when its below frezzeing all works fine till gets to serten temp

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  • abujon2000 Jan 22, 2009

    i have the same problem with my 1999 A6 Audi, Engine and the Abs light comes on with dropping of the revs thus making the ac unoprative.

  • Joe Smiith
    Joe Smiith Feb 07, 2009

    same problem i tried freezer spray on abs modulator bosch part number0273004285 the problem goes away to return when unit warm again also heavy braking brings it on immediatly plus just fitted second hand modulator same problem and supplier says ha checked it before shipping and i believe him so problem is definately from modulator when warm but must be other fault but shows when modulator is warm ddriving me nuts will check power supply to abs in case its only marginal otherwise stumped on this one

  • Anonymous Feb 13, 2009

    transmission problem

  • Anonymous Mar 13, 2014

    audi a6 rev counter not working


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You have a thermal fault i the abs modulator <ecu bolted onto pump> the rev counter fails because this signal fails to get from 13.8 volts to zero it only manages to get to about 3 volts this is very common on bosch 5 series mine had pt code bosch 0273004285 and is notorious but easil removed and sent to bba here in uk or others in usa you will have to remove wheel then washer bottle then modulator but car stiill drives when removed the esp needs signal from abs and fails at same time also loss of tacho signal puts il light on i tried to find second hand one biut they didnt work have sent mine for repair<you need a microscope to do it> will post when it comes back ps easily confirmed by spraying abs pump.modulator with freex=zer spray did it to mine and fault dissappears untill warm again nb even when cold i bet if you brake hard a couple of times it will fail please let me know if your pt number is same as mine and if this heelps it drove me nuts

Posted on Feb 26, 2009

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I have an Audi A3 2006. It has starting problems when starting from a warm engine. Always starts when cold. It is fully serviced and had all the recommended repairs/ maintaince done when required. It is baffling even the mechanics who have had it in their service depot for 3 weeks now. Any suggestions out there?

Posted on Apr 14, 2011

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I found out on the net that it was an failure in the ABS-ECU (seemed to be common for this type) and had it repaired by ABB in Germany, now it works perfect again.

Posted on Apr 03, 2009

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I would check charging voltage when this happens. The voltage at the battery should be around 14 volts engine running. If there is a drop in voltage, this can affect the vehicle control units, bringing on warning lights. Check it at tickover and at a higher rpm, if there is a significant difference say 3 volts, then replace the alternator.


Posted on Jan 25, 2009

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