Wednesday, November 02, 2016 - 10:14 pm, by: Raoul Duke(Hunter)
EFI code 21 indicates a fault in the Exhaust O2 sensor (in the exhaust downpipe of a TT), most likely failure of the sensor but possible a damaged signal wire or bad connection. I assume 22 is another O2 sensor. EFI code 52 indicates a fault with the #1 knock sensor (in the front LHS of the block of a TT.)