Manifold Air Pressure Sensor (Map Sensor)

On CRX Si, disconnect vacuum hose No. 21 (hose between throttle body and MAP sensor) at throttle body. Plug fitting in throttle body. Connect vacuum pump to open end of vacuum hose. On all models, unplug wiring harness connector from control unit. Connect System Checker Harness (07999-PD60000A ).
On CRX Si, apply vacuum to MAP sensor. On all models, turn ignition on. Connect digital voltmeter positive probe to C15 terminal on Prelude, C11 terminal on all other models, of system checker harness and negative probe to C14 terminal. Measure voltage between terminals.
On Prelude, if reading is not 4.75-5.25 volts, replace ECU. If voltage was 4.75-5.25 volts, connect positive rest lead to C11 terminal and negative lead to C14 terminal. If reading is not 2.76-2.96 volts, repair open or short in wire between MAP sensor and C11, C14 or C15 terminals on ECU. If wire are okay, replace MAP sensor.
On all other models, voltage should be as indicated in MAP SENSOR VOLTAGE (ALL EXCEPT PRELUDE) table. If not, replace MAP sensor.

MAP SENSOR VOLTAGE (ALL EXCEPT PRELUDE)

Fig 1: Testing Manifold Air Pressure Sensor Civic CRX Si models shown.