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.
DTC P0657: General Description
Main CPU and driver ICs are built into the powertrain control module (PCM). The main CPU receives drive commands and driver IC drives each corresponding devices. Power for the main CPU is provided from +B P/P VBU line via CPU power supply, and power for the driver ICs are provided from FI MAIN RLY OUT line via PGM-FI main relay 1 circuit. If the FI MAIN RLY OUT voltage is a specified voltage for a specified time, the PCM detects a malfunction and stores a DTC.
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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.
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