Code No. P244A: DPF Differential Pressure Too Low


FUNCTION



  • The engine-ECU monitors the difference between exhaust gas pressures at the inlet and outlet of the DPF by using the exhaust differential pressure sensor.
  • If the difference is abnormally low, the engine-ECU will determine that the DPF is melted down or missing.

TROUBLE JUDGMENT


Check Condition
  • Battery positive voltage is 8 - 16 V.
  • 2 seconds later after the ignition switch has been in "ON" position or the engine has started up.
  • The No. 2 exhaust gas temperature sensor temperature (catalyst temperature) exceeds the specified value.
  • The No. 3 exhaust gas temperature sensor temperature (DPF temperature) exceeds the specified value.
  • Exhaust flow rate exceeds the specified value.
  • Engine speed is within the predetermined range.
  • Final fuel injection quantity exceeds the specified value.
Judgement Criterion
  • DPF differential pressure is below the specified value.

FAIL-SAFE AND BACKUP FUNCTION



  • The DPF regeneration is prohibited.

PROBABLE CAUSE



  • The exhaust pressure hose or the exhaust pressure pipe is disconnected or damaged.

  • The DPF melted down.

  • The DPF missing.

DIAGNOSIS PROCEDURE

STEP 1. Check exhaust pressure hose and exhaust pressure pipe.

  • Check the lines between the exhaust differential pressure sensor and the DPF (i.e, exhaust pressure hose and exhaust pressure pipe) for disconnection or damage.

Q. Are the check results normal?
Replace the DPF.
Repair or replace the exhaust pressure hose or exhaust pressure pipe.