Hi, please forgive me for barging in here and asking questions straight away.

Im 18 from Liverpool in the UK.... My grandad has a 2000 A4 1.8
The engine light recently came on about a week ago, I got a friend to read the codes for me.... it threw up the codes:

17545 - Fuel Trim: Bank 1 (Add): System too Rich
and
18010 P1602 Power Supply (B+) Terminal 30 - Low Voltage

Iwas wondering if someone could explain these to me, and tell me what may need doing to the car?

Thanks for your time! Alex.

 

17545 is often due to unmetered air entering the system, one of the common reasons is the MAF sensor. I had it happen when I installed an over-oiled K&N filter. The oiled contaminated the MAF sensor and since the air entering the system could not be properly metered, I threw the 17545 DTC.
18010 has happened to me as well after leaving the battery disconnected a long time to perform work on the car. After a ride to allow the alternator to recharge the battery, I cleared the code with VAG-COM and it didn't come back. (old battery?)

 

just a guess but sounds like battery power was too low or disconnected P1602,

this could cause the EVAP to fail due to lack of power to activate the canister purge valve 17545/ P1137.

possible fault could be poor connection to the + terminal on the battery