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 P1658: Electronic Throttle Control System (ETCS) Control Relay ON Malfunction
- Turn the ignition switch ON (II).
- Do the ETCS TEST in the INSPECTION MENU with the HDS.
Is the RELAY circuit OK?
YES - Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the ETCS control relay and the ECM/PCM.
NO - Go to step 3.
- Turn the ignition switch OFF.
- Remove the ETCS control relay (F) from the under-hood fuse/relay box.
- Test the ETCS control relay (see POWER RELAY TEST
).
Is the ETCS control relay OK?
YES - Go to step 6.
NO - Replace the ETCS control relay, then go to step 13.
- Jump the SCS line with the HDS.
- Disconnect ECM/PCM connector A (44P).
- Check for continuity between ECM/PCM connector terminal A20 and body ground.
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there continuity?
YES - Repair short in the wire between the ECM/PCM (A20) and the ETCS control relay, then go to step 13.
NO - Go to step 9.
- Disconnect ECM/PCM connector C (44P).
- Turn the ignition switch ON (II).
- Measure voltage between ECM/PCM connector terminal C1 and body ground.
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there battery voltage?
YES - Repair short to power in the wire between the ECM/PCM (CD and the ETCS control relay, then go to step 12.
NO - Go to step 18.
- Turn the ignition switch OFF.
- Reconnect all connectors.
- Turn the ignition switch ON (II).
- Reset the ECM/PCM with the HDS.
- Do the ECM/PCM idle learn procedure (see ECM/PCM IDLE LEARN PROCEDURE ).
- Check for Temporary DTCs or DTCs with the HDS.
Is DTC P1658 indicated?
YES - Check for poor connections or loose terminals at the ETCS control relay and the ECM/PCM, then go to step 1.
NO - Troubleshooting is complete. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTCs troubleshooting.
- Turn the ignition switch OFF.
- Reconnect all connectors.
- Update the ECM/PCM if it does not have the latest software (see ECM/PCM UPDATE ), or substitute a known-good ECM/PCM (see SUBSTITUTING THE ECM/PCM ).
- Check for Temporary DTCs or DTCs with the HDS.
Is DTC P1658 indicated?
YES - Check for poor connections or loose terminals at the ETCS control relay and the ECM/PCM. If the ECM/PCM was updated, substitute a known-good ECM/PCM (see SUBSTITUTING THE ECM/PCM ), then recheck. If the ECM/PCM was substituted, go to step 1.
NO - If the ECM/PCM was updated, troubleshooting is complete. If the ECM/PCM was substituted, replace the original ECM/PCM (see ECM/PCM REPLACEMENT ). If any other Temporary DTCs or DTCs are indicated, go to the indicated DTCs troubleshooting.
NO RELATED
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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.