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Home >> Honda >> 1991 >> Civic Si >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Diagnostic Codes >> Code 3 - Map Sensor

Code 3 - Map Sensor

  1. Turn off ignition. Remove ECU fuse for 10 seconds to reset ECU. Start engine. Verify if CHECK ENGINE light is on and if LED is flashing Code 3. If LED is flashing Code 3, go to next step. If LED is not flashing Code 3, problem is intermittent. Check connectors at MAP sensor and ECU.
  2. Turn ignition off. Disconnect 3-wire MAP sensor connector. Turn ignition on. Measure voltage between Yellow/Red (+) wire and ground. If reading is about 5 volts, go to step 4).
  3. If reading is not approximately 5 volts, check for open in Yellow/Red (+) wire between ECU terminal C15 and MAP sensor. If wire is okay, substitute a known good ECU, and recheck. If specified voltage is now available, replace original ECU.
  4. Measure voltage between Yellow/Red (+) and Green/White (-) wires. If voltage is about 5 volts, go to step 5). If reading is not about 5 volts, check for open in Green/White wire between ECU terminal C14 and MAP sensor. If wire is okay, substitute a known good ECU, and recheck. If specified voltage is now present, replace original ECU.
  5. Measure voltage between White (+) and Green/White (-) wires. If reading is not about 5 volts, go to step 7). If measured voltage is about 5 volts, turn ignition off. Reconnect 3-wire MAP sensor connector. Connect ECU Test Harness (07999-PD6000A ) between ECU and ECU connector. See Figure . Turn ignition on. Measure voltage between terminal C11 (+) and C14 (-). See Figure . If reading is not about 3 volts, replace MAP sensor.
  6. If about 3 volts are present between terminals C11 and C14, substitute a known good ECU, and recheck. If specified voltage is now available, replace original ECU.
  7. If voltage measured in step 5) is not about 5 volts, repair open or short in White wire between ECU terminal C11 and MAP sensor. If wire is okay, substitute a known good ECU, and recheck. If specified voltage is now available, replace original ECU.
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