P0037 fault code on double decat system??
 

Hi there. First time user here!! I have recently purchased a 2002 subaru wrx fitted with an STI engine which has been de catted and re mapped allegedly by andy forrest. The obd light has come on and is showing the fault code POO37 which indicates rear oxygen sensor heater circuit malfunction. After speaking to andy on the phone he told me if it was him who had genuinely re mapped the car he would have mapped the light out so can any one help me here? If the car was mapped to accomodate this happening would the light still come on or is the previous keeper pulling my chain about who re mapped it or am i looking at something more serious here? The car is driving fine. Hope someone can help.