The engine-ECU monitors the signals input from the rail pressure sensor.
The engine-ECU controls the suction control valve so that necessary fuel pressure can be obtained before fuel injection.
The engine-ECU compares the fuel pressure immediately before fuel injection and the fuel pressure after injection to check whether. The pressure drop greatly exceeds the expected range determined based on fuel consumption. The engine-ECU detects fuel leaks in this way.
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 engine speed is 600 r/min or more
Rail pressure sensor is normal
The fuel discharge rate of the supply pump continues to exceed its threshold value against the fuel injection rate.
Fuel leakage or fuel line blocked
Failed suction control valve
Failed rail pressure sensor.
Harness damage in rail pressure sensor circuit or loose connector contact.
STEP 1. M.U.T.-III diagnosis code
Is any other diagnosis code than P0093 set?
STEP 2. Detection of fuel line leakage
Check whether fuel is leaking from a high-pressure fuel line.
Is the check result normal?
STEP 3. Release the air from the fuel line.
After releasing the air from the fuel line, continue idle operation for about five minutes and recheck for trouble symptoms.