Faulty remote accessory module (internal failure or corrupted software); Damaged or corroded wiring between the remote accessory module and the network bus; Poor electrical connections at the module harness or ground points; Low battery voltage or charging system issues causing modules to send invalid data; Network bus faults (shorted or open data lines) affecting communication; Aftermarket accessories improperly installed and interfering with the remote accessory module; Water intrusion or physical damage to the remote accessory module

DTC codes / U05xx · Network communication / U0549

U0549Invalid Data Received From Remote Accessory Module

Q: What does code U0549 mean?

Invalid Data Received From Remote Accessory Module. U0549 indicates that a control module received invalid or corrupted data from the remote accessory module over the vehicle's communication network. The remote accessory module typically handles functions like keyless entry, remote start, or other convenience features, and the receiving module detected that the data frames were missing, out of range, or failed checksum validation.

U0549 indicates that a control module received invalid or corrupted data from the remote accessory module over the vehicle's communication network. The remote accessory module typically handles functions like keyless entry, remote start, or other convenience features, and the receiving module detected that the data frames were missing, out of range, or failed checksum validation.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaNetwork communication

Symptoms you may notice

Warning light on the dashboard, often the check engine light or a dedicated accessory system warning
Remote start or keyless entry functions may stop working or behave erratically
Intermittent operation of accessories such as power liftgate, sunroof, or memory seats
No noticeable symptoms besides the warning light in some cases
Other modules may log communication codes or show unexplained electrical glitches

Common causes, most likely first

Faulty remote accessory module (internal failure or corrupted software)
Damaged or corroded wiring between the remote accessory module and the network bus
Poor electrical connections at the module harness or ground points
Low battery voltage or charging system issues causing modules to send invalid data
Network bus faults (shorted or open data lines) affecting communication
Aftermarket accessories improperly installed and interfering with the remote accessory module
Water intrusion or physical damage to the remote accessory module

How to diagnose and fix it

Perform a full scan of all modules to identify which module set U0549 and check for related communication codes
Inspect the remote accessory module harness and connectors for corrosion, loose pins, or damage
Test the battery and charging system to rule out low voltage as a cause of invalid data
Check the network bus wiring for shorts, opens, or excessive resistance using a multimeter
If wiring and power are good, reflash or update the remote accessory module software if applicable
Substitute a known-good remote accessory module to confirm the fault before replacement
Clear codes and verify the repair by test-driving and rechecking for the code

Before you replace the remote accessory module

A weak battery or failing alternator can cause modules to send corrupted data, so always verify charging system health before condemning the module.
Aftermarket remote starters or alarm systems spliced into the network are a frequent culprit and often cause this code without any factory component failure.
The code may be stored in a module other than the remote accessory module itself, so scanning all modules is essential to locate the true source.
Corroded ground connections can create voltage drops that corrupt data signals, mimicking a failed module.
U0549 can be an intermittent code that only appears under certain conditions, so a road test with live data monitoring may be needed to reproduce it.

Can I keep driving with U0549?

The vehicle is generally safe to drive because the fault affects accessory convenience features rather than critical systems, but avoid relying on remote start or keyless entry until repaired. If the warning light is accompanied by other electrical symptoms, have the vehicle inspected promptly.

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.