Disconnecting the battery should not give any errors.
The proper procedure is:-
Switch the vehicle off and wait 20 minutes, then disconnect the negative lead, then disconnect the positive lead, then using a jump lead (piece of wire that has two crocodile clips) join the positive and negative leads together and leave them for 15 minutes. After 15 minutes remove the jump lead (crocodile clips) and reconnect the positive lead to the battery terminal and tighten up, then reconnect the negative lead to the battery and tighten up. Start up the engine.
Jump lead with crocodile clips.....
Must not be connected to any terminals that are still connected to a battery
