VESPA GTS Super 125 i.e. Service Station Manual page 109

Vespa GTS Super 125 i.e.
THE FOLLOWING INFORMATION REFER TO THE VERSION EQUIPPED WITH MIU G3 ECU.
LAMBDA PROBE
Function
In charge of telling the control unit whether the
mixture is lean or rich.
Operation / Operating principle
Based on the difference of oxygen in the exhaust
fumes and the environment, this generates volt-
age which is read and interpreted by the injection
control unit.
Pin-out:
1. Positive from control unit
2. Negative from control unit
ELECTRICAL ERRORS
Check the air-fuel ratio / Lambda probe P0130 - Shorted to positive / open circuit, shorted to negative
or carburetion excessively lean / signal not plausible for abnormal title correction or probe signal fault.
Error cause
Short circuit to positive: excessive voltage at PIN 11 or PIN 12 of the control unit connector.
Circuit open or short circuit to negative: interruption of the circuit or null voltage between control unit
connector PIN 11 and 12.
Troubleshooting
Short circuit to positive:
- Disconnect the control unit connector and the sensor connector.
- Verify that there is no short circuit with the battery positive on the PIN 1 of the sensor connector
(corresponding to the PIN 11 of the control unit connector); in the presence of short circuit, restore the
cable harness.
- Verify that there is no short circuit with the battery positive on the PIN 2 of the sensor connector
(corresponding to the PIN 12 of the control unit connector); in the presence of short circuit, restore the
cable harness.
Open circuit:
- Disconnect the control unit connector and the sensor connector.
- Check the continuity of the cable harness between the sensor connector and control unit connector:
PIN 11 of the control unit - PIN 1 of the sensor and PIN 12 of the control unit - PIN 2 of the sensor. If
necessary, restore the cable harness.
- If the cable harness is intact and the error persists, proceed with the following checks.
Short circuit to negative:
- Disconnect the sensor connector and the control unit connector.
- Check the sensor connector PIN 1 ground insulation. If there is no insulation, restore the cable harness.
Electrical system
ELE SYS - 109