my bonnet is stuck fast how can i open it.
Thermostat may not be opening to allow coolant to flow through heater box. Thermostat may be opening too soon allowing cold coolant to flow through heater box. Either way thermostat needs replacing
Your air mass flow meter may need replacing. The way to test is to open the bonnet then start the car. After you have started it pull the plug from the air mass flow meter. This is a plug connected up to the air intake of the engine, just after the air filter, and before the engine. If as soon as you pull it out the rev counter settles (the engine will revert to a default setting once it loses the output from the air mass flow meter) then you should have the air mass flow meter changed at the eariest oppourtinity. They cost about £100, and you would be much better off getting it done by a small private company so Audi don't rip you off. My Audi mechanic friend tells me its a common problem with these cars and Audi will charge £350 for the job.
DO NOT REMOVE THE BUMPER! which is what a tech from Audi told me to do...
the light will turn out by a hinge on the side closest to the grille. once you pull on the housing from the tire well side it should open away from the car like a door. (i removed the entire bumper to find this out.....)
um, i have a 2007 a3, i don't know about any earlier years