how to fix B1121 code in Honda Civic 11th Generation (2022-Present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to avoid accidental airbag deployment.
• Wait at least 3 minutes after disconnecting the battery before proceeding.

2. Inspect Wiring and Connectors

• Remove the passenger seat from the vehicle using a socket set (typically 12mm).
• Check the wiring harness underneath the seat for any visible damage or disconnections.
• Ensure all connectors are securely attached and free from corrosion.

3. Test Seat Weight Sensor

• Locate the passenger seat weight sensor, which is usually integrated into the seat cushion.
• Use a multimeter to test the resistance across the sensor terminals, ensuring it meets the manufacturer's specifications (typically between 0.5-3.5 ohms).
• If the sensor is out of specification, proceed to replace it.

4. Replace Seat Weight Sensor (if necessary)

• Carefully remove the seat cushion cover to access the weight sensor.
• Disconnect the weight sensor wiring harness.
• Replace the sensor with a new one, ensuring correct orientation and secure connections.
• Reassemble the seat cushion cover.

5. Reinstall Passenger Seat

• Position the passenger seat back in the vehicle and secure it with the bolts.
• Reconnect the negative battery terminal.
• Clear the B1121 code using the OBD-II scanner.