Yamaha YZF-R125 Service Manual: Troubleshooting method

The engine operation is not normal and the engine trouble warning light comes on.

1. Check:

  • Fault code number

a. Check the fault code number displayed on the FI diagnostic tool.

b. Identify the faulty system with the fault code.

Refer to "Self-Diagnostic Function table".

c. Identify the probable cause of the malfunction.

Refer to "Diagnostic code table".

2. Check and repair the probable cause of the malfunction.


3. Perform fuel injection system reinstatement action.

Refer to "Reinstatement method" of table in "TROUBLESHOOTING DETAILS" on page 8-41.

4. Set the main switch to "OFF" and back to "ON", and then check that no fault code number is displayed.

NOTE:

If other fault codes are displayed, repeat steps (1) to (4) until no fault code number is displayed.

5. Erase the malfunction history in the diagnostic mode. Refer to "Sensor operation table (Diagnostic code No. 62)".

NOTE:

Setting the main switch to "OFF" will not erase the malfunction history.

The engine operation is not normal but the engine trouble warning light does not come on.

1. Check the operation of the following sensors and actuators in the diagnostic mode. Refer to "Sensor operation table" and "Actuator operation table".


If a malfunction is detected in the sensors or actuators, repair or replace all faulty parts.

If no malfunction is detected in the sensors and actuators, check and repair the inner parts of the engine.

    Self-diagnostic function table
    If the ECU detects an abnormal signal from a sensor while the vehicle is being driven, the ECU illuminates the engine trouble warning light and provides the engine with alternate operating instru ...

    Diagnostic mode
    It is possible to monitor the sensor output data or check the activation of actuators with the FI diagnostic tool connected to the vehicle and set to the normal mode or the diagnostic monitoring ...

    Other materials:

    Starting circuit cut-off system operation
    If the engine stop switch is set to " " and the main switch is set to "ON" (both switches are closed), the starter motor can only operate if at least one of the following conditions is met: The transmission is in neutral (the neutral switch is closed). The clutch lever is pulled to the ...

    Adjusting the rear disc brake
    1. Check: Brake pedal position (distance "a" from the center of the rider footrest to the center of the brake pedal) Out of specification Adjust. 2. Adjust: Brake pedal position a. Loosen the locknut "1". b. Remove the cotter pin "2", washer "3", and pin "4". c. Turn t ...

    Checking the ignition spark gap
    1. Check: Ignition spark gap Out of specification Perform the ignition system troubleshooting, starting with step 5. Refer to "TROUBLESHOOTING" on page 8-3. NOTE: If the ignition spark gap is within specification, the ignition system circuit is operating normally. a. Disconnect the spa ...

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