GM-Multec ECU Fault Codes
This fault code chart shows the GM-Multec fault codes for the following systems:- SPi, MPi, CFi, M
and S.
GM-Multec Code Chart:
Code: Item: Fault:
12 Initiation of diagnosis. n/a
13 Oxygen sensor No change in voltage/open circuit.
14 Coolant Temperature Sensor (CTS) Low voltage
15 Coolant Temperature Sensor (CTS) High voltage
16 Knock signal circuit n/a
18 Knock control processor n/a
19 Crank Angle Sensor (CAS) Incorrect RPM signal
21 Throttle Potentiometer Sensor (TPS) High voltage
22 Throttle Potentiometer Sensor (TPS) Low voltage
24 Vehicle Speed Sensor (VSS) No speed signal or low voltage
25 Injector valve Low voltage
28 Fuel pump relay contacts Contact problem
29 Fuel pump relay Low voltage
32 Fuel pump relay High voltage
Manifold Absolute Pressure (MAP)
33 High voltage
sensor
Manifold Absolute Pressure (MAP)
34 Low voltage
sensor
35 Idle stepper motor Poor or no idle speed control
Amplifier control signal, cylinders 2 and 3
41 High voltage
(Direct Ignition System (DIS))
Amplifier control signal, cylinders 1 and 4
42 High voltage
(Direct Ignition System (DIS))
43 Primary ignition (distributor systems) High voltage
44 Oxygen sensor Air/Fuel mixture too lean (weak)
45 Oxygen sensor Air/Fuel mixture too rich
Amplifier (Direct Ignition System (DIS))
46 High voltage
control signal (A+B)
Linear exhaust gas re-circulation (EGR)
47 n/a
position
Battery supply to Engine Control Unit
49 High voltage (greater than 17 volts)
(ECU)
Defective ECU (disconnect and reconnect (ECU),
51 Engine Control Unit (ECU)
then recheck for fault codes). Memory failure
52 Secondary air pump relay Low voltage
53 Secondary air pump relay High voltage
54 Idle Carbon Monoxide (CO) n/a
potentiometer
55 Engine Control Unit (ECU) fault Renew Engine Control Unit (ECU)
56 Air control soleniod Low voltage
57 Air control soleniod High voltage
61 Fuel tank vent valve (FTVV) Low voltage
62 Fuel tank vent valve (FTVV) High voltage
Amplifier control signal, cylinders 2 and 3
63 Low voltage
(Direct Ignition System (DIS))
Amplifier control signal, cylinders 1 and 4
64 Low voltage
(Direct Ignition System (DIS))
65 Primary ignition (distributor systems) Low voltage
66 Throttle position sensor (TPS) Hose broken
Air Flow Sensor (AFS), hot wire meter Signal is outside normal operation parameters (out
67
(air mass meter) of range)
Air Flow Sensor (AFS), hot wire meter
68 Faulty air mass meter signal, incorrect frequency
(air mass meter)
Air Temperature Sensor (ATS) (MPi
69 Low voltage
only)
Air Temperature Sensor (ATS) (MPi
71 High voltage
only)
Amplifier (Direct Ignition System (DIS))
72 Lead interruption, open circuit
control signal (A+B)
Torque control (Automatic Transmission
75 Low voltage
(AT) only)
Torque control (Automatic Transmission
76 Continuous
(AT) only)
81 Injector valve High voltage
83 Immobiliser No or wrong code
84 Immobiliser No signal
85 Immobiliser Wrong signal
87 Air conditioning cut-off relay Low voltage
88 Air conditioning cut-off relay High voltage
92 Camshaft sensor Faulty hall effect sensor or circuit
93 Quad drive module (in ECU) n/a
