U0128 means Lost Communication With Park Brake Control Module. Other modules on the vehicle network have stopped receiving messages from the park brake control module. The electronic parking brake may not apply or release normally. It is a generic OBD-II code, so the definition is the same on any make, but the most likely cause varies by engine; confirm with a scan tool and the service information for your vehicle before buying parts.
What U0128 means
Modern vehicles have many control modules that share information over a network, usually called the CAN bus. Codes starting with U mean a module has stopped hearing another one, and voltage and processor codes mean a module is not getting clean power or has an internal fault. Low battery voltage, poor grounds, blown fuses and damaged wiring cause many of these codes, so test the battery and charging system first.
U0128 symptoms
- Warning lights for the affected system
- Features controlled by that module not working
- Check engine light on some vehicles
Common causes of U0128
- Low battery voltage or a recent jump-start
- Blown fuse or failed power or ground to the module
- Network wiring or connector damage
- Failed module
How to diagnose U0128
- Check battery voltage and the module’s fuses
- Check the module’s power and ground
- Scan all modules to see which can and cannot communicate
- Inspect network wiring near the module
Can you drive with U0128?
It depends on which system is affected; have safety systems such as brakes, airbags or steering checked promptly.
U0128 tips
Electronic parking brake modules may need a service mode for brake work; follow the procedure to avoid communication faults.
Will U0128 clear itself?
If the fault stops, the computer turns off the check engine light by itself after several drive cycles without seeing it again, and the code stays in memory as history for a while. Clearing U0128 with a scan tool after a repair is fine, but if the cause is still there the code returns, sometimes within one drive. Disconnecting the battery also clears codes on most vehicles, but it erases learned fuel trims and idle settings as well.
Related codes
| Code | Meaning |
|---|---|
| U0100 | Lost Communication With ECM/PCM A |
| U0101 | Lost Communication With TCM |
| U0121 | Lost Communication With Anti-Lock Brake System (ABS) Control Module |
Guides that help
When it is more than a sensor
Voltage and network codes come from wiring, the battery, the charging system or a module, not from engine or transmission wear. If a lost-communication code has left the transmission in limp mode, rule out the module and wiring before deciding the unit has failed, and see our transmissions only if testing confirms internal damage.
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