On my 2018 GDI disconnecting the battery does not cause the engine light to come on. You can do as JohnV6 suggests or get a cheap reset tool, this should also tell you what the error code is.
Yes, the fuel gauge can get upset when you disconnect the battery, it depends on what the digital display (in the speedo) is set to when the battery is disconnected. Are you saying the fuel gauge is reading near to empty? If yes reset the fuel gauge.
To reset the fuel gauge, turn the ignition on and set the digital display to the odometer reading. Turn the ign off. Disconnect the battery ( I alway disconnect the negative) for about 10 seconds. Reconnect the battery. Turn the ign on again and the fuel gauge should be correct.
Cheers
John
PS edit, just remembered, pressing the button on the speedo with the battery connected but the ignition off will cause the fuel gauge to be reset to zero regardless of how much fuel is in the tank.
Last edited by John07; 17/12/22 05:58 PM.
