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
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.
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.
