Diesel Diagnostic Equipment

Detroit Diesel: Removal of the Diesel Exhaust Fluid Lines (Tank to Pump)

Removal of the Diesel Exhaust Fluid Lines is an important component of servicing your DEF system.

NOTICE: Discard contaminated Diesel Exhaust Fluid (DEF) and coolant in accordance with Environmental Protection Agency (EPA) regulations.

NOTICE: Wait at least five minutes after shutting down the engine to disconnect the battery ground cable. Disconnecting the battery ground cable too soon will prevent purging of the DEF lines after the engine is shut down.

  1. Shut off engine and apply the parking brake, chock the wheels, and perform any other applicable safety steps.
  2. Disconnect the batteries
  3. Place drain pans underneath the Diesel Exhaust Fluid (DEF) pump and the DEF metering unit to catch any draining DEF.

NOTICE: To disconnect a DEF line, push the line coupling in towards the male connector to move the holding clip to the unlocked position, then compress the prongs of the holding clip and pull the line off of the male connector. Failure to properly remove a DEF line can result in damage to a line coupling or DEF port.

  1. Disconnect the DEF line heater wiring harnesses (1) at the tank and the pump.
  2. Disconnect the DEF lines (3,4) between the DEF pump and the tank.
  3. Disconnect the DEF lines between the DEF pump and the metering unit.
  4. Discard the lines.
  5. Ensure the new DEF lines are undamaged and free of dirt, debris, or DEF crystals.
  6. Remove any white DEF crystals from the DEF ports on the tank, pump, and metering unit.

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