99 audi a6 2.4 oil light and abs flashes, rev counter stops working and auto box malfunctions.

most problems come from the cam and crank sensor, these control the engine, that intern controls the auto box, there is also a speed sensor on the auto box this controls gear change and works with the abs and road speed sensor work from the abs, 3-5 then drops can be the sensor not reading correctly as 2-3 is safe mode, these sensors can last a few years but if older than 5 years and depending on miles or engine use they will need changing as the engine heats up and cools down. auto box sensor is located on the auto box. most gear changing problems are down to this or the gear oil needs changing. you can buy a live data reader cheap these days that will work with your model these are handy as you can connect it and read what the ecu is doing and record the live data to find the correct problem, you may have a problem but its still within the promoters for the ecu settings and not register a fault. hope this info helps you.

with the motor running?your problem is vague but whatever it is be sure to check the fuses and if they check out ok get a good auto-electrician to take a look at your vehicle

if the ABS fault light comes on as you turn on the ignition and control unit can't be accessed with a fault reader then the control unit itself is faulty and must be repaired or replaced. if can be accessed, should store a fault in the memory, most probably in a wire to wheel speed sender. if light comes on only after vehicle is in motion than fault will be a dirty or incorrectly adjusted speed sender.

i would check the throttle butterfly for a carbon build up that may keep it from closing completely. have seen this cause stalling when returning to idle rpm. Best to try to remove and clean from both sides to get good results.this is just one of many possible problems. Hope it helps if so please let me know with a reply and good luck

could be either or both take to trans tech for test and reading of trans code

i have audi a6 2005 ,i turn the key to start noting happen, the lights on the dash does not come on, i checked the battery is good, when the key is on on position the stearing wheel is not unlocked

replace the brake switch.i has seen in gm cars if brake switch is open not working.it will cause anti lock brakes stop working.see if anti lock brake module detect fault in brake switch circuit .anti lock brakes stop working.your brake light and abs light will come on.if this dont help.take it to dealership.

The engine could be shot, oil is being burnt off by the actions of being sucked into the bores via worn piston rings then ejected out of the exhaust

If you sent the car in for an MOT and a Service I would ask the garage what they did to it as the car would have failed on its emissions test if that much oil was coming out .

It could have been a fault on the oil pump or lack of oil in the first instance and maybe an overfill on the service

You paid your money now go back for redress

hia nick....sounds crazy but change or check for a mass air meter fault...99% thats what it will be....good luck matt

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