Yamaha YZF-R125 Service Manual: Intake air pressure sensor

1. Check:

  • Intake air pressure sensor output voltage Out of specification Replace the throttle body.

a. Connect the pocket tester (DC 20 V) to the throttle body sensor assembly coupler as shown.


  • Positive tester probe
    pink/white "1"
  • Negative tester probe
    gray/black "2"

Intake air pressure sensor


b. Set the main switch to "ON".

c. Measure the intake air pressure sensor output voltage.

    Throttle position sensor
    1. Check: Throttle position sensor a. Connect the digital circuit tester to the terminals of the throttle body sensor assembly coupler as shown. Positive tester probe → gray/red t ...

    Intake air temperature sensor
    1. Check: Intake air temperature sensor resistance Out of specification Replace the throttle body. a. Connect the pocket tester ( × 1k) to the throttle body sensor assembly co ...

    Other materials:

    Checking the starter motor operation
    1. Check: Starter motor operation Does not operate → Perform the electric starting system troubleshooting, starting with step 4. Refer to "TROUBLESHOOTING" on page 8-9. a. Connect the positive battery terminal "1" and starter motor lead "2" with a jumper lead "3". W ...

    Main switch/steering lock
    Main switch/steering lock The main switch/steering lock controls the ignition and lighting systems, and is used to lock the steering. The various positions are described below. ON All electrical circuits are supplied with power, the meter lighting, taillight, license plate light and ...

    Installing the valves
    The following procedure applies to all of the valves and related components. 1. Deburr: Valve stem end (with an oil stone) 2. Lubricate: Valve stem "1" Valve stem seal "2" (with the recommended lubricant) 3. Install: Lower spring seat "1" Valve stem seal "2" V ...

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