Mitsubishi LANCER EVOLUTION-IV 1998, Workshop Manual, Page: 236 / 526

MPI –
Troubleshooting
13-13
Code No. 25 Barometric pressure sensor system Probable cause
Range of Check
D
Ignition switch: ON
D
Excluding 60 seconds after the ignition switch is turned to ON or immediately
after the engine starts.
Set conditions
D
Sensor output voltage is 4.5 V or more (corresponding to a barometric pressure
of 114 kPa {855 mmHg} or more) for 4 seconds.
or
D
Sensor output voltage is 0.2 V or less (corresponding to a barometric pressure
of 53 kPa {40 mmHg} or less) for 4 seconds.
D
Malfunction of the barometric pressure sensor
D
Improper connector contact, open circuit or
short-circuited harness wire of the barometric pressure
sensor circuit
D
Malfunction of the engine-ECU
OK
Replace the air flow sensor.
Measure at the air flow sensor con-
nector A-25.
D
Connect the connector. (Use
the test harness: MB991709)
D
Voltage between 2 and earth
(Ignition switch: ON)
OK: 3.7– 4.3 V (Altitude: 0 m)
3.2– 3.8 V
(Altitude: 1,200 m)
NG
Measure at the air flow sensor con-
nector A-25.
D
Disconnect the connector, and
measure at the harness side.
D
Voltage between 1 and earth
(Ignition switch: ON)
OK: 4.8– 5.2 V
D
Continuity between 5 and earth
OK: Continuity
NG
Check the following connector:
B-62
NG
Repair
OK
Check trouble symptom.
NG
Check the harness wire between
the engine-ECU and the baromet-
ric pressure sensor connector.
NG
Repair
OK
Replace the engine-ECU.
OK
Check the following connector:
A-25
NG
Repair
OK
Check trouble symptom. Check the harness wire between
the engine-ECU and the baromet-
ric pressure sensor connector.
NG
Repair
OK
Measure at the engine-ECU con-
nector B-62.
D
Connect the connector.
D
Voltage between 85 and earth
(Ignition switch: ON)
OK: 3.7– 4.3 V (Altitude: 0 m)
3.2– 3.8 V
(Altitude: 1,200 m)
NG
Check the harness wire between
the engine-ECU and the baromet-
ric pressure sensor connector, and
repair if necessary.
Check the following connec-
tors:
A-25, B-62
OK
Check trouble symptom.
NG
Replace the engine-ECU.
NG
Repair
OK
NG