What it means
A control module has received data from the cruise control module that it considers invalid or implausible. Cruise-control functions may be affected; the specific effects depend on the vehicle.
At a glance
- Usually lights the warning light of the system that lost communication
How it works
The cruise control module manages cruise functions and shares its status with other vehicle modules. U0405 is set when a receiving module rejects data from the cruise control module as implausible or incompatible with the expected software or configuration.
Common causes
Most likely first.
- Implausible or incorrect cruise control module data
- Software or configuration incompatibility
- Intermittent network data corruption
Symptoms
- Cruise control may be unavailable
- Related warning indicators may illuminate
- A diagnostic scan may show related communication codes
How to diagnose it
- Scan all modules and save freeze-frame data to identify which module logged U0405 and whether cruise control codes are also present.
- Check live cruise control status and switch inputs to see whether the reported state matches the driver's commands.
- Inspect the cruise control module connectors, grounds, and network wiring for corrosion, looseness, or damage.
- Check the module's power and network communication, including any related communication faults in other modules.
- If wiring and power are sound, verify the cruise control module's software and configuration and investigate any module fault indicated by related codes.
Common fixes
- Repair a damaged or poorly connected cruise control module connector, ground, or network wire.
- Correct incompatible cruise module software or configuration.
- Repair a faulty cruise control switch or module if testing shows it is producing invalid status data.
- Replace an incorrectly specified module and configure it for the vehicle.
Can I keep driving?
Cruise control may be unavailable or may cancel unexpectedly, but normal driving can often continue if the vehicle otherwise responds normally. Do not rely on cruise control until the fault is resolved, and stop if any broader vehicle-control warning or abnormal behavior appears.
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.