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 JUDGEMENT

Check Condition

The engine is stable (various factors such as engine speed, fuel injection amount, intake air flow, exhaust gas temperate are within a predetermined range).
Exhaust gas flow exceeds a predetermined value.
Estimated PM accumulated deposit, which is calculated from a current estimated engine exhaust PM amount, exceeds a predetermined value.
The distance travelled since the last DPF regeneration exceeds a predetermined value.

Judgement Criterion

The difference between exhaust gas pressures at the inlet and outlet of the DPF remains smaller than the pressure difference which is estimated during no PM accumulation in the DPF for a predetermined duration.

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 in the catalytic converter assembly 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 catalytic converter assembly (DPF) (i.e, exhaust pressure hose and exhaust pressure pipe) for disconnection or damage.

Q. Are the check results normal?

	Replace the catalytic converter assembly.

	Repair or replace the exhaust pressure hose or exhaust pressure pipe.