engine management light

[sliderz a4]

recently bought 2008 (57) a4 2.0 tdi 170 avant s-line, on day 2 of ownership engine management light came on :mad:, when plugged into diagnostics code PO115 appears ( engine coolant temperature sensor) , a local garage has fitted 3 different genuine audi sensors but the fault still appears, he has checked all the wiring & connectors & everything looks to be good, when the fault is cleared it comes back onto the diagnostics straight away as soon as the engine is started, then the management light comes on again :confused: the car has been plugged into 3 different diagnostics but all say the same fault.. today it was plugged into a friends laptop and once again up comes PO115 coolant temp sensor but also code PO135 appears ( bank 1 lambda sensor) :confused::confused: only thing I have noticed is my fuel economy is very poor with only 22mpg around town & 35mpg at 70 mph on dual carriageway.. help!!

[zollaf]

we can possibly presume that the sensor is not the cause of the fault. has anyone looked at live data to see what temperature is being recorded by the ecu. this would help to narrow things down. is it one constant default reading of around 50 degress or does it vary. next job is to study a wiring diagram and continuity tes the wires from the sensor to the ecu. checking the wires visually is a start but you won't see inside to see if one is broken internally.

[slippyr4]

What diagnostics is your garage using? Some generic OBD thing? If so, I'd get a scan done with VCDS or the proper VW one - generic OBD scan tools are like trying to get a doctor to diagnose a disease using only a wooden spoon.

[sliderz a4]

I have had it scanned again today using VCDS & once again code PO115 appeared , im going to have to bite the bullet & take it to an auto electrician.. :mad: not a good start to my audi relationship..