Code C0691 on the 2020 Infiniti QX60 indicates a malfunction in the rear right air suspension valve circuit. This solenoid valve controls air flow to the rear right air spring, enabling ride height adjustment and automatic load leveling for this corner of the vehicle.
Valve Circuit Operation
The air suspension control module commands the rear right valve to open or close based on height sensor input and driver requests. Opening the valve allows compressed air to flow into the spring, raising that corner. The control module precisely manages valve timing to achieve and maintain target ride heights.
Symptoms Observed
With C0691 active, the suspension warning light illuminates and a message appears on the dashboard. The rear right corner may not adjust properly - potentially sitting too low or unable to rise when loaded. The automatic load-leveling function that keeps the vehicle level when cargo is added will be compromised.
Diagnostic Investigation
Verify the fault by commanding valve operation through a Nissan/Infiniti diagnostic tool. Monitor system pressure and height while commanding the valve - a working valve should produce observable height changes. Test electrical continuity to the valve and check coil resistance. Inspect for contamination in the air system that could cause mechanical valve failure.
Repair Approach
Valve solenoids are typically replaceable without replacing the entire valve block. Locate the valve block, identify the rear right valve, and replace if faulty. Ensure the air system is depressurized before disassembly. After repairs, purge air from lines and perform system calibration.