U0466 indicates that a control module—typically the powertrain or body computer—has received corrupted, implausible, or missing data from the rear HVAC control module over the vehicle’s communication network. The code sets when a message fails a checksum validation or contains values outside expected parameters, flagging a data integrity fault rather than a specific mechanical failure.
Corroded, bent, or loose pins in the module connector, or chafed and shorted CAN bus wiring between the rear HVAC module and the network backbone, are the most common source of data corruption.
The module’s internal transceiver or processor may generate invalid data packets due to water intrusion, thermal damage, or circuit board failure.
Weak battery or erratic alternator output can drop voltage below the module’s operating threshold during cranking or high-load conditions, causing garbled transmissions.
Non-original alarm systems, chargers, or lighting wired into the CAN bus can inject noise that corrupts messages between modules.
If all wiring and the sending module test good, the receiving control module may have a rare internal network fault, but this is an uncommon cause for this specific code.
No. The PCM is rarely the cause. This code almost always stems from wiring issues or a faulty rear HVAC control module. Only consider the PCM after exhaustive testing of the network and the sending module.
Yes. The vehicle remains drivable, but rear climate functions may be disabled or operate incorrectly. The code does not typically affect engine performance.
It means the receiving module got a message from the rear HVAC module, but the data failed a validation check—such as a checksum error or out-of-range values—indicating the message was corrupted during transmission or generated incorrectly.
If the fault was intermittent—such as a temporary loose connector—the code may become stored and turn off the warning light after several key cycles. Persistent hardware failures will keep the code active.