I changed the MAF sensor and the IAT sensor on the cold side intercooler pipe. Those codes went away. I then changed out the DEF injector line that goes from the exhaust to the def heater to clear the P20bd code. I now am getting a code P1201 injector circuit open/shorted. The dealer we got the truck from said he fixed this issue before we bought it. They reimbursed me for the maf sensor and iat sensor and are gonna come get the truck and see whats going on. I am just curious as to what the voltage should be at the injector harness. I tested it and was getting 4.7 volts? this seemed low to me. Glad they are gonna fix it just curious what you guys think.