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 MANUALSHONDA2020CIVIC SI, 4D SEDANREPAIR AND DIAGNOSIS (SINGLE PAGE)BODY & FRAMEDOOR LOCKSSECURITY SYSTEM / KEYLESS ENTRY SYSTEM - GEN INFO & TROUBLESHOOTING
2020 Honda Civic Si, 4D Sedan
Security System / Keyless Entry System - Gen Info & Troubleshooting
2020 Honda Civic Si, 4D SedanSECTION Security System / Keyless Entry System - Gen Info & Troubleshooting
- Symptom Troubleshooting
- Keyless/Power Door Locks/Security System Symptom Troubleshooting - AUTO DOOR UNLOCK does not work (4-door)
- Keyless/Power Door Locks/Security System Symptom Troubleshooting - AUTO DOOR UNLOCK does not work (5-door) (2017 2018 2019 2020 2021)
- Keyless/Power Door Locks/Security System Symptom Troubleshooting - Doors automatically relock 30 seconds after being unlocked with the remote even though a door has been opened (2-door) (2016 2017 2018 2019 2020)
- Keyless/Power Door Locks/Security System Symptom Troubleshooting - Doors automatically relock 30 seconds after being unlocked with the remote even though a door has been opened (4-door)
- Keyless/Power Door Locks/Security System Symptom Troubleshooting - Doors automatically relock 30 seconds after being unlocked with the remote even though a door has been opened (5-door) (2017 2018 2019 2020 2021)
- Keyless/Power Door Locks/Security System Symptom Troubleshooting - Security alarm system will not arm (2-door) (2016 2017 2018 2019 2020)
- Keyless/Power Door Locks/Security System Symptom Troubleshooting - Security alarm system will not arm (4-door)
- Keyless/Power Door Locks/Security System Symptom Troubleshooting - Security alarm system will not arm (5-door) (2017 2018 2019 2020 2021)
- Keyless/Power Door Locks/Security System Symptom Troubleshooting - The horn does not sound and/or the headlights do not flash when the PANIC button on the remote is pressed
- Description & Operation
- Immobilizer System Description - Components
- Immobilizer System Description - Control/Function
- Immobilizer System Description - System Diagram
- Keyless Access System Description - Components (2/4-door)
- Keyless Access System Description - Components (5-door) (2017 2018 2019 2020 2021)
- Keyless Access System Description - Control/Function (2/4-door)
- Keyless Access System Description - Control/Function (5-door) (2017 2018 2019 2020 2021)
- Keyless Access System Description - Failsafe Function
- Keyless Access System Description - System Diagram (2/4-door)
- Keyless Access System Description - System Diagram (5-door) (2017 2018 2019 2020 2021)
- Keyless/Power Door Locks/Security System Description - Components (2/4-door)
- Keyless/Power Door Locks/Security System Description - Components (5-door) (2017 2018 2019 2020 2021)
- Keyless/Power Door Locks/Security System Description - Control/Function (2/4-door)
- Keyless/Power Door Locks/Security System Description - Control/Function (5-door) (2017 2018 2019 2020 2021)
- Keyless/Power Door Locks/Security System Description - Overview
- Keyless/Power Door Locks/Security System Description - System Diagram (2/4-door)
- Keyless/Power Door Locks/Security System Description - System Diagram (5-door) (2017 2018 2019 2020 2021)
- Symptom Troubleshooting Index for Viewer
- All the doors will not lock and unlock
- All the doors will not lock or unlock with driver's door key cylinder or door lock switch or keyless transmitter/remote (2-door) (2016 2017 2018 2019 2020)
- All the doors will not lock or unlock with driver's door key cylinder or door lock switch or keyless transmitter/remote (4-door)
- All the doors will not lock or unlock with driver's door key cylinder or door lock switch or keyless transmitter/remote (5-door) (2017 2018 2019 2020 2021)
- Auto door unlock does not work (2-door) (2016 2017 2018 2019 2020)
- Auto door unlock does not work (4-door)
- Auto door unlock does not work (5-door) (2017 2018 2019 2020 2021)
- Cannot select ON mode with keyless access and with the keyless remote touching the engine start/stop switch
- Cannot select ON mode with keyless access, but can select ON mode with the keyless remote touching the engine start/stop switch
- Cannot select ON mode with the keyless remote touching the engine start/stop switch, but can select ON mode with keyless access
- Doors automatically relock 30 seconds after being unlocked with the remote even though a door has been opened (2-door) (2016 2017 2018 2019 2020)
- Doors automatically relock 30 seconds after being unlocked with the remote even though a door has been opened (4-door)
- Doors automatically relock 30 seconds after being unlocked with the remote even though a door has been opened (5-door) (2017 2018 2019 2020 2021)
- Driver's door will not lock or unlock (2-door) (2016 2017 2018 2019 2020)
- Driver's door will not lock or unlock (4-door)
- Driver's door will not lock or unlock (5-door) (2017 2018 2019 2020 2021)
- Engine does not crank (power supply is normal)
- Engine start/stop switch does not work
- Front passenger's and right rear doors will not lock or unlock (4-door)
- Front passenger's and right rear doors will not lock or unlock (5-door) (2017 2018 2019 2020 2021)
- Left rear door will not lock or unlock (4-door)
- Left rear door will not lock or unlock (5-door) (2017 2018 2019 2020 2021)
- Passenger doors will not unlock with the remote or key cylinder switch, but will unlock with the inside door unlock switch (2-door) (2016 2017 2018 2019 2020)
- Passenger doors will not unlock with the remote or key cylinder switch, but will unlock with the inside door unlock switch (4-door)
- Passenger doors will not unlock with the remote or key cylinder switch, but will unlock with the inside door unlock switch (5-door) (2017 2018 2019 2020 2021)
- Passenger's door will not lock or unlock (2-door) (2016 2017 2018 2019 2020)
- Security alarm system will not arm (2-door) (2016 2017 2018 2019 2020)
- Security alarm system will not arm (4-door)
- Security alarm system will not arm (5-door) (2017 2018 2019 2020 2021)
- Security indicator blinks
- The doors will not unlock or lock with the door outer handle touch sensor or lock switch, but will unlock or lock with the keyless remote
- The doors will not unlock or lock with the keyless remote, but will unlock or lock with the door outer handles
- The engine starts, but stalls immediately
- The horn does not sound and/or the headlights do not flash when the PANIC button on the keyless transmitter/remote is pressed (2-door) (2016 2017 2018 2019 2020)
- The horn does not sound and/or the headlights do not flash when the PANIC button on the keyless transmitter/remote is pressed (4-door)
- The horn does not sound and/or the headlights do not flash when the PANIC button on the keyless transmitter/remote is pressed (5-door) (2017 2018 2019 2020 2021)
- The mode changes between ACCESSORY and ON, but it does not change to OFF
- The mode changes between ACCESSORY and ON, but it is difficult to change to OFF
- The security system sounds randomly while the doors are locked (2-door) (2016 2017 2018 2019 2020)
- The security system sounds randomly while the doors are locked (4-door)
- The security system sounds randomly while the doors are locked (5-door) (2017 2018 2019 2020 2021)
- Troubleshooting
- Circuit Diagrams
- HomeLink Remote Control System Circuit Diagram
- Immobilizer System Circuit Diagram (2/4-door)
- Immobilizer System Circuit Diagram (5-door) (2017 2018 2019 2020 2021)
- Keyless Access System Circuit Diagram (2/4-door)
- Keyless Access System Circuit Diagram (5-door) (2017 2018 2019 2020 2021)
- Keyless/Power Door Locks/Security System Circuit Diagram (2/4-door with Keyless Access System)
- Keyless/Power Door Locks/Security System Circuit Diagram (2/4-door without Keyless Access System)
- Keyless/Power Door Locks/Security System Circuit Diagram (5-door with Keyless Access System) (2017 2018 2019 2020 2021)
- Keyless/Power Door Locks/Security System Circuit Diagram (5-door without Keyless Access System) (2017 2018 2019 2020 2021)
- Servicing
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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.