Dodge P1721 Control Relay Description OBD-II Trouble Code Description for P1721 Dodge Control Relay PSA OBD-II Trouble Code Description for P1721 Dodge Gear 1 Incorrect ratio VAG OBD-II Trouble Code Description for P1721 Dodge Wheel Speed Signal 3 Range/Performance OBD-II Trouble Code Description for P1721 Dodge Control module cooling fan Signal too high