OBDII/EOBD diagnostics trouble codes definition
If your car supports OBD II or EOBD, then you can already use almost 5000 generic OBDII codes. These codes are from PowerTrain series (P0XXX, P2XXX, P34XX), Body Series (B0XXX), Chassis series (C0XXX), Network series (U0XXX, U2XXX, U3XXX).
Also there is a list of more than 13500 additional manufacturer specific codes.
Nitrogen oxides (NOX) sensor - heater control - short to earth