1998 Audi A4 Gas Odor

Look around the injectors and at any fittings under the hood. IF you smell fuel, there is probably a leak and it needs to be found. Any check engine light? Wondering if it is just running too rich instead of leaking. When was the last tune up? Does it feel like it is missing at all?

Normally the PCM will store a code that says too rich, but if the coolant sensor is bad, that will also cause the problem

If you don't have an actual fuel leak and the engine is running rich the CTS could be the cause if it doesn't switch from open loop mode meaning the computer will constantly be giving the engine fuel when not needed.

I strongly recommend have your fuel pressure checked. Could be a bad fuel pressure regulator or a clogged fuel return line overpressurizing it-excessive fuel pressure.

Running rich should throw out a code P0172 and/or P0175. Typical symptoms of an engine that is running rich (too much fuel, not enough air) are poor fuel economy, elevated emissions (Carbon monoxide or CO), and engine may have rough idle or surge condition.

Possible causes include a bad O2 sensor, excessive fuel pressure (bad fuel pressure regulator or plugged return line), leaky fuel injectors, dirty air filter or restricted air inlet, or a defective coolant sensor that prevents the engine management system from going into closed loop mode.