Mitsubishi Lancer Evolution IX. Manual - part 419

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-151

Code No. P0325: Detonation Sensor System

OPERATION

• The sensor signal is inputted to the engine-ECU 

(terminal No. 91) from the detonation sensor (ter-
minal No. 1).

FUNCTION

• The detonation sensor detects the vibration of the 

cylinder block caused by detonation waves, and 
inputs a signal to the engine-ECU.

• In response to the signal, the engine-ECU pro-

vides controls to retard the ignition timing when 
the detonation occurs.

TROUBLE JUDGMENT

Check Conditions

• Ignition switch: "ON"

• Excluding for 2 seconds after ignition switch is set 

to "ON" position or 2 seconds after engine start is 
completed.

• The engine speed is 2,000 r/min. or more.

• The volumetric efficiency is 30% or more.

Judgment Criterion 

• The change amount of the detonation sensor out-

put voltage (the detonation sensor peak voltage 
in every half a turn of the crankshaft) is below 
0.06 V or less in 200 consecutive times.

2

1

AK501811

80

87

81

94

85

82

84

93

86

98

99

74

92

73

83

88

91

95

97

96

100

89

78

71

90

76 77

75

72
79

91

W

B

B

Detonation sensor

2

1

Engine-ECU

Detonation sensor circuit

Wire colour code
B: Black  LG: Light green  G: Green  L: Blue  W: White  Y: Yellow  SB: Sky blue  BR: Brown  O: Orange  GR: Gray
R: Red  P: Pink  V: Violet  PU: Purple

C-117

(MU803783)

AB

B-108

MU802661

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-152

PROBABLE CAUSES

• Failed detonation sensor

• Open/short circuit in detonation sensor circuit or 

loose connector contact

• Failed engine-ECU 

DIAGNOSIS PROCEDURE

STEP 1. Connector check: B-108 detonation 
sensor connector

Q: Is the check result normal? 

YES : 

Go to Step 2 .

NO : 

Repair or replace the connector.

STEP 2. Perform resistance measurement at 
B-108 detonation sensor connector.

• Disconnect connector, and measure at harness 

side.

• Resistance between terminal No. 2 and earth.

OK: 2 

Ω or less

Q: Is the check result normal? 

YES : 

Go to Step 3 .

NO : 

Check and repair harness between B-108 

(terminal No. 2) detonation sensor 
connector and body earth.

• Check earthing line for open circuit 

and damage.

AK305019

1

2

AB

Connector : B-108

Harness side 
connector

B-108(GR)

Detonation sensor

AK305019

1

2

AB

Connector : B-108

Harness side 
connector

B-108(GR)

Detonation sensor

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-153

STEP 3. Connector check: C-117 engine-ECU 
connector

Q: Is the check result normal? 

YES : 

Go to Step 4 .

NO : 

Repair or replace the connector.

AK501996

80

87

81

94

85

82

84

93

86

98

99

74

92

73

83

88

91

95

97 96

100

89

78

71

90

76

77

75

72
79

AB

Connector: C-117

C-117 (GR)

C-117 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-154

STEP 4. Check harness between B-108 (terminal 
No. 1) detonation sensor connector and C-117 
(terminal No. 91) engine-ECU connector.

• Check output line for open/short circuit and dam-

age.

Q: Is the check result normal? 

YES : 

Go to Step 5 .

NO : 

Repair the damaged harness wire.

STEP 5. Check the trouble symptoms.

Q: Does trouble symptom persist?

YES : 

Go to Step 6 .

NO : 

Intermittent malfunction (Refer to GROUP 
00 

− How to Use 

Troubleshooting/Inspection Service Points 

P.00-5

).

STEP 6. Replace the detonation sensor.

• After replacing the detonation sensor, re-check 

the trouble symptoms.

Q: Does trouble symptom persist?

YES : 

Replace the engine-ECU.

NO : 

The check is end.

AK305019

1

2

AB

Connector : B-108

Harness side 
connector

B-108(GR)

Detonation sensor

AK501996

80

87

81

94

85

82

84

93

86

98

99

74

92

73

83

88

91

95

97 96

100

89

78

71

90

76

77

75

72
79

AB

Connector: C-117

C-117 (GR)

C-117 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>