Does C1B40 mean the right side radar sensor is bad?

No. Nissan uses this DTC as a trouble area indicator for the right side radar function. The left rear side radar can set it when it cannot validate the right radar’s data or status. Confirm power, ground, and connector pin fit first. Then check scan-tool status for the right radar and look for related network or voltage codes.

Can my scan tool communicate with the right side radar module, and why does it matter?

Communication matters because “no communication” points to wiring, power/ground, or network faults before sensor failure. If the scan tool cannot enter the right radar module, check fuses, module power and ground, and network continuity at the radar connector. If it communicates but shows internal faults or implausible targets, focus on mounting, blockage, or sensor integrity.

Will I need calibration after repairing C1B40?

Often, yes. Any radar replacement, bracket replacement, bumper cover change, or impact repair can require Nissan calibration or initialization. Use a scan tool that supports Nissan ADAS functions and follow the service procedure for aiming and confirmation. Do not skip this step. A mis-aimed radar can miss vehicles or trigger false alerts, which creates a safety risk.

How do I verify the repair is complete and the code will not return?

Clear the DTC only after you correct the cause. Then confirm the right side radar shows “ready/normal” in live data and no pending DTCs appear. Drive the Leaf under conditions that allow radar self-checks to run, which vary by Nissan enable criteria. Use service information for exact requirements. Recheck for stored and pending codes after the drive.

What is the first physical check I should do before buying parts?

Inspect the rear bumper and quarter area for harness damage and water entry. Unplug the radar-related connectors and check for corrosion, bent pins, and poor terminal tension. Verify the bumper cover does not block the radar zone and the bracket sits straight. Many C1B40 cases trace to connector issues or misalignment after minor body work, not sensor failure.

C1B40 Nissan – Side radar (right) fault

C1109 Battery voltage
C1145 Yaw rate sensor
C1705 Low pressure (right front)
C1706 Low pressure (right rear)
C1707 Low pressure (left rear)
C1A16 Radar stain (Component or system operation obstructed or blocked)
C1B00 Camera unit malf
C1B52 Right blind spot warning (BSW)/blind spot intervention (BSI) indicator…

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