Audi a6 on board computer reading faults

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

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?

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.

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.

TL