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.
2021 Honda Pilot EX-L, FWDFACTORY OEM SERVICE PROCEDURE
Keyless Access Control Unit
KEYLESS ACCESS CONTROL UNIT DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION
| DTC | Description | DTC type |
|---|---|---|
| B1601 | Keyless access control unit internal (CPU) error | Internal error |
| B1602 | Keyless access control unit internal (EEPROM) error | Internal error |
| B1632 | MTR CONT signal error | Signal error |
| B1640 | RF1 antenna not connected or malfunction | Signal error |
| B1645 | Driver's door LF antenna circuit short | Signal error |
| B1646 | Driver's door LF antenna circuit open | Signal error |
| B1647 | Passenger's door LF antenna circuit Short | Signal error |
| B1648 | Passenger's door LF antenna circuit open | Signal error |
| B1649 | Driver side rear passenger door LF antenna circuit short | Signal error |
| B1650 | Driver side rear passenger door LF antenna circuit open | Signal error |
| B1651 | Passenger side rear passenger door LF antenna circuit short | Signal error |
| B1652 | Passenger side rear passenger door LF antenna circuit open | Signal error |
| B1659 | Front interior LF antenna circuit short | Signal error |
| B1660 | Front interior LF antenna circuit open | Signal error |
| B1663 | Rear interior LF antenna circuit short | Signal error |
| B1664 | Rear interior LF antenna circuit open | Signal error |
| U1280 | Keyless Access Control Unit communication Bus Line Error (BUS-OFF) | Loss of communication |
| U1281 - Refer to: DTC Troubleshooting: U1281, U128D (Keyless Access Control Unit) (2019 2020 2021) or DTC Troubleshooting: U1281, U128D (Keyless Access Control Unit) (2016 2017 2018) . |
Keyless access control unit lost communication with MICU | Loss of communication |
| U128D - Refer to: DTC Troubleshooting: U1281, U128D (Keyless Access Control Unit) (2016 2017 2018) DTC Troubleshooting: U1281, U128D (Keyless Access Control Unit) (2019 2020 2021) or . |
Keyless access control unit lost communication with gauge control module | Loss of communication |
Factory Service Tools
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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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