Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSHONDA2005CIVIC SI L4-2.0LREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTRELAYS AND MODULES - POWERTRAIN MANAGEMENTRELAYS AND MODULES - COMPUTERS AND CONTROL SYSTEMSENGINE CONTROL MODULETESTING AND INSPECTIONPROGRAMMING AND RELEARNINGECM/PCM IDLE LEARN PROCEDURE
2005 Honda Civic Si L4-2.0L
ECM/PCM Idle Learn Procedure
2005 Honda Civic Si L4-2.0LSECTION ECM/PCM Idle Learn Procedure
ECM Idle Learn Procedure
The idle learn procedure must be done so the ECM can learn the engine idle characteristics.
Do the idle learn procedure whenever you do any of these actions:
- Disconnect the battery
- Replace the ECM or disconnect its connector.
- Clean or replace the throttle body.
- Reset the ECM.
NOTE: Erasing DTCs with the HDS does not require you to do the idle learn procedure.
- Remove the No.6 ECU (ECM) (15 A) fuse from the under-hood fuse/relay box.
- Remove the No.19 battery (80 A) fuse from the under-hood fuse/relay box.
- Remove PGM-FI main relay 1.
- Remove any of the wires from the under-hood fuse/relay box.
- Disconnect any of the connectors from the under-hood fuse/relay box.
- Disconnect the connector between the engine compartment wire harness and ECM wire harness.
- Disconnect the G2 terminal from the transmission housing.
- Disconnect the G1 terminal from the body.
- Disconnect the G101 terminal from the cylinder head cover.
Procedure
1. Make sure all electrical items (A/C, audio, rear defogger, lights, etc.) are off.
2. Start the engine, and hold it at 3,000 rpm without load (in neutral) until the radiator fan comes on, or until the engine coolant temperature reaches 194 °F (90 °C).
3. Let the engine idle for about 5 minutes with the throttle fully closed.
NOTE: If the radiator fan comes on, do not include its running time in the 5 minutes.
The idle learn procedure must be done so the ECM can learn the engine idle characteristics.
Do the idle learn procedure whenever you do any of these actions:
- Disconnect the battery
- Replace the ECM or disconnect its connector.
- Clean or replace the throttle body.
- Reset the ECM.
NOTE: Erasing DTCs with the HDS does not require you to do the idle learn procedure.
- Remove the No.6 ECU (ECM) (15 A) fuse from the under-hood fuse/relay box.
- Remove the No.19 battery (80 A) fuse from the under-hood fuse/relay box.
- Remove PGM-FI main relay 1.
- Remove any of the wires from the under-hood fuse/relay box.
- Disconnect any of the connectors from the under-hood fuse/relay box.
- Disconnect the connector between the engine compartment wire harness and ECM wire harness.
- Disconnect the G2 terminal from the transmission housing.
- Disconnect the G1 terminal from the body.
- Disconnect the G101 terminal from the cylinder head cover.
Procedure
1. Make sure all electrical items (A/C, audio, rear defogger, lights, etc.) are off.
2. Start the engine, and hold it at 3,000 rpm without load (in neutral) until the radiator fan comes on, or until the engine coolant temperature reaches 194 °F (90 °C).
3. Let the engine idle for about 5 minutes with the throttle fully closed.
NOTE: If the radiator fan comes on, do not include its running time in the 5 minutes.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.