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.
Main Relay (Computer/Fuel System): Description and Operation
2005 Honda Civic L4-1.7L CNGSECTION Description and Operation
PGM-FI Main Relay 1 and 2
The PGM-FI relay consists of two separate relays. PGM-FI main relay 1 is energized whenever the ignition switch is ON (II). It supplies battery voltage to the PCM, powers injectors, and powers PGM-FI main relay 2. PGM-FI main relay 2 is energized to supply power to the fuel pressure regulator shut-off solenoid valve/fuel tank internal solenoid valve for 2 seconds when the ignition switch is turned ON (II), and when the engine is running.
The PGM-FI relay consists of two separate relays. PGM-FI main relay 1 is energized whenever the ignition switch is ON (II). It supplies battery voltage to the PCM, powers injectors, and powers PGM-FI main relay 2. PGM-FI main relay 2 is energized to supply power to the fuel pressure regulator shut-off solenoid valve/fuel tank internal solenoid valve for 2 seconds when the ignition switch is turned ON (II), and when the engine is running.
RENDER: 1.0x
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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.