Corroded, loose, or damaged electrical connector at the mirror control module or at the mirror assemblies; Chafed or broken wiring in the door harness or the flexible boot between the door and body, where wires flex repeatedly; Failed mirror control module B, often due to water intrusion or internal circuit board faults; Low battery voltage or a weak charging system causing modules to reboot and send corrupted data; A faulty power mirror switch or motor that draws excessive current and disrupts the module's data output; Network bus wiring faults, such as a shorted or open data line, that corrupt messages from the mirror module; Aftermarket accessories or improper electrical repairs that introduce interference on the communication bus

DTC codes / U04xx · Invalid data received from a module / U044F

U044FInvalid Data Received From Mirror Control Module B

Q: What does code U044F mean?

Invalid Data Received From Mirror Control Module B. U044F is a communication fault indicating that a control module on the vehicle's network received invalid or corrupted data from the mirror control module B, which manages power mirror functions such as adjustment, folding, and heating. The receiving module detected that the data frames from the mirror module did not match the expected format, checksum, or signal range, so it flagged the message as invalid rather than acting on it.

U044F is a communication fault indicating that a control module on the vehicle's network received invalid or corrupted data from the mirror control module B, which manages power mirror functions such as adjustment, folding, and heating. The receiving module detected that the data frames from the mirror module did not match the expected format, checksum, or signal range, so it flagged the message as invalid rather than acting on it.

SystemNetwork

Code typeGeneric (all makes)

SeverityLow

Fix difficultyIntermediate

AreaInvalid data received from a module

Symptoms you may notice

Power mirror adjustments may stop responding or move erratically on one or both sides
Mirror heating, folding, or auto-dimming functions may fail to operate
The mirror control module may be completely unresponsive to switch inputs
A warning light or message may appear on the dash, though often no symptoms besides the warning light are noticed
Other modules on the same network may log communication codes if the mirror module is disrupting the bus
Memory seat or mirror position recall may not work correctly if the mirror module shares that function

Common causes, most likely first

Corroded, loose, or damaged electrical connector at the mirror control module or at the mirror assemblies
Chafed or broken wiring in the door harness or the flexible boot between the door and body, where wires flex repeatedly
Failed mirror control module B, often due to water intrusion or internal circuit board faults
Low battery voltage or a weak charging system causing modules to reboot and send corrupted data
A faulty power mirror switch or motor that draws excessive current and disrupts the module's data output
Network bus wiring faults, such as a shorted or open data line, that corrupt messages from the mirror module
Aftermarket accessories or improper electrical repairs that introduce interference on the communication bus

How to diagnose and fix it

Verify battery voltage and charging system output, as low voltage is a common cause of spurious communication codes
Inspect and clean the mirror control module connector and the connectors at each mirror for corrosion or loose pins
Check the door harness and the boot between the door and body for chafed, broken, or shorted wires
Use a scan tool to clear the code and observe live data from the mirror module to see if the fault returns immediately
Perform a voltage drop or resistance test on the network bus wires at the mirror module to rule out wiring faults
If wiring and power are good, substitute a known-good mirror control module or perform a module swap to confirm the fault
After repair, clear all codes and verify that the mirror functions work and that no communication codes return after a test drive

Why mirror module data goes invalid

A door harness wire that flexes every time the door opens is a frequent culprit, and the damage is often hidden inside the rubber boot where visual inspection misses it
Water intrusion into the mirror housing or the module connector can corrupt data without blowing a fuse, so the mirror may still move but send invalid position feedback
The code can be set by a module that is not the mirror module itself, because the receiver flags invalid data, so testing only the mirror module can miss a bus fault elsewhere
Low voltage from a weak battery or a failing alternator can cause multiple modules to log U-codes, and replacing the mirror module will not fix the root cause
Aftermarket LED lighting or phone chargers plugged into the accessory socket can introduce electrical noise that corrupts network messages on some vehicles

Can I keep driving with U044F?

The vehicle remains safe to drive because the fault affects convenience features, not steering, braking, or airbags, but avoid relying on mirror adjustments and have the fault diagnosed soon to prevent the communication issue from spreading to other modules.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.