B1646 The keyless access unit saw an open in the driver door low frequency antenna circuit
What does B1646 mean on a Honda?
B1646. The keyless access unit saw an open in the driver door low frequency antenna circuit. The smart key may not be detected at the driver door. This Honda-enhanced code applies to Honda and Acura models that use this code.
Common causes of B1646
- Faulty driver door low frequency antenna
- Driver door low frequency antenna harness is open or shorted
- Driver door low frequency antenna circuit poor electrical connection
- Faulty keyless access control unit
- Corroded or loose connector pins at the antenna
How to fix B1646
- Confirm the code with a scan tool and check the smart key at that location
- Inspect the antenna connector and wiring for corrosion, moisture, and loose pins
- Test the antenna circuit for an open or short with a multimeter
- Check the wiring before replacing the antenna
- Replace the driver door low frequency antenna if it fails testing, then clear codes and retest
Sources and review
- Last updated 2026-09-29.