PROBABLE CAUSES:

For 2007 EPA Engines:1. Engine brake solenoid.2. Short to ground between pin 91 of the ECM 120-pin connector and the valve cover fuel injector harness connector (31-pin connector).3. Short to ground between pin 22 of the 31-pin connector on the vehicle side of he harness and the fan control solenoid.4. Short to ground between pin 93 of the ECM 120-pin connector and the air seal pressure regulator valve cover.5. Failed air seal pressure regulator valve.

For 2010 EPA Engines:1. Inspect the connectors on: DEF pump, pressure limiting unit, diffuser heater, and DEF injection valve.2. ACM2 (Aftertreatment Control Module) failure.3. Short to ground between pins 1, 3, or 5 of the ACM2 and pin 2 of the corresponding components.4. Reconnect components from line #1 one at a time and clear the code after each connection. When the code goes active, this is your failed part.

For 2014 EPA Engines:1. Engine Jake brake solenoid failure.2. Front under valve cover fuel injector harness.3. Short to ground between pin 91 of the 120-pin ECM connection and the valve cover fuel injector harness connector (31-pin).4. Short to ground between pin 22 of the 31-pin connector on the vehicle side of the harness and fan control solenoid.5. Short to ground between pin 93 of the 120-pin ECM connection and the air seal pressure regulator valve connector.6. Air seal pressure regulator valve.