Engine light on 1999 1.8 T

Interesting. That code doesn't exist in the ECU error code tables for that engine/model year, at least according to the Audi repair manual. In fact there are no codes listed that start with "174.."

Any chance you or your VAG are dyslexic and the code is really 17544 "Long Term Fuel Trim Add, Fuel, Bank 1 System too Lean"?

/daytripper '00 s4 6spd

sorry my dyslexic...you're right again as usual....17544

does this mean i need a tune up?

I think this is asking for more than a "tune up". It looks like something's either aged out of range or you have a leaky hose.

Here's what's listed in the repair manual DTC troubleshooting procedure for ECO code 17544:

- Check intake air system for leaks ("false air")

- Check HO2S ("Heated Oxygen Sensor") and O2S control

- Check Mass Air Flow (MAF) sensor

- Check fuel pressure regulator and residual fuel pressure

- Check fuel injectors

- Output Diagnostic Test Mode (DTM) (aka "the last resort")

To be honest, unless you can find an induction system leak, without a service manual you've got little chance of finding the root cause of the problem - and even with one it's going to take some work.

On the up side, air leaks are not uncommon, but then again, so are MAFs that have aged beyond usable condition...

/daytripper '00 s4 6spd

I vote the little hose from the intake manifold down to the turbo! You might be able to hear the leak as a HISS!

I had looked for that DTC too! Thought it was a joke! lol