What it means
A receiving module detected implausible data from the rear HVAC control module. Temperature setpoint, blower or vent values fail plausibility checks and are rejected.
How it works
The rear HVAC control module sends rear temperature settings and operating information, such as blower or vent status, to other modules. A receiving module sets U0466 when rear HVAC data falls outside its plausibility checks and is rejected.
Common causes
Most likely first.
- Module internal fault or sensor input drift
- Software version mismatch after replacement
- Gateway module routing CAN messages incorrectly
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
How to diagnose it
- Scan all modules and save freeze-frame data and communication codes to identify which module rejected the rear HVAC message.
- Compare live rear temperature setpoint, blower, and vent data with the controls and actual rear HVAC response.
- Inspect the rear HVAC control module connectors and wiring for loose pins, corrosion, or damage, especially where the harness runs to the rear of the vehicle.
- Check for CAN or gateway faults that could disrupt messages from the rear HVAC module.
- If wiring and network checks pass, verify rear HVAC sensor inputs and module software compatibility using the manufacturer's diagnostic procedure.
Common fixes
- Repair damaged or poorly connected rear HVAC module wiring or terminals.
- Restore a poor power or ground connection to the rear HVAC module.
- Correct the software configuration of a replaced rear HVAC module.
- Repair or replace a faulty rear HVAC sensor or control module if its data remains implausible.
- Repair a gateway or CAN network fault affecting rear HVAC messages.
Can I keep driving?
If only rear climate control is affected, driving is generally possible, though rear occupants may lose heating, cooling, or airflow control. Address it promptly if other vehicle systems show warnings or enter a reduced-function mode.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.