Inlet Air Pressure Sensor (Service Code 12)
If the wiring is good, check the sensor for various vacuum.
Remove the inlet air pressure sensor [A] and disconnect
the vacuum hose from the sensor.
Connect an auxiliary hose [B] to the inlet air pressure sen-
Temporarily install the inlet air pressure sensor.
Connect a digital meter [C], vacuum gauge [D], the fork
oil level gauge [E] and the harness adapter to the inlet air
Special Tools - Fork Oil Level Gauge: 57001-1290
Vacuum Gauge: 57001-1369
Sensor Harness Adapter: 57001-1561
Inlet Air Pressure Sensor Output Voltage
Connections to Adapter:
Digital Meter (+) → G/W (sensor Y/BL) lead
Digital Meter (–) → BK (sensor BR/BK) lead
Turn the ignition switch ON.
Measure the inlet air pressure sensor output voltage from
various vacuum readings, while pulling the handle of the
fork oil level gauge.
Check the inlet air pressure sensor output voltage, using
the following formula and chart.
Pg: Vacuum Pressure (Gauge) of Throttle Body
Pl: Local Atmospheric Pressure (Absolute) measured by
Pv: Vacuum Pressure (Absolute) of Throttle Body
Vv: Sensor Output Voltage (V)
Pv = Pl – Pg
For example, suppose the following data is obtained:
Pg = 8 cmHg (Vacuum Gauge Reading)
Pl = 70 cmHg (Barometer Reading)
Vv = 3.2 V (Digital Meter Reading)
Pv = 70 – 8 = 62 cmHg (Absolute)
Plot this Pv (62 cmHg) at a point  on the chart and draw a
vertical line through the point. Then, you can get the usable
range  of the sensor output voltage.
Usable range = 3.08 ∼ 3.48 V
Plot Vv (3.2 V) on the vertical line. → Point .
Results: In the chart, Vv is within the usable range and
the sensor is normal.
If the reading is out of the usable range, replace the sen-
If the reading is within the usable range, check the ECU
for its ground and power supply (see ECU Power Supply
If the ground and power supply are good, replace the ECU
(see ECU Removal/Installation).
FUEL SYSTEM (DFI) 3-53