What it means
A receiving module detected implausible data from chassis control module B. Vehicle dynamics, ride-height or damper command values fail plausibility checks and are rejected.
At a glance
- Usually lights the warning light of the system that lost communication
- The engine or gearbox may go into limp mode
How it works
Chassis control module B sends vehicle-dynamics information, which may include ride-height or damper-control data depending on the vehicle. U042C is set when a receiving module finds module B's data implausible and rejects it; possible sources include a module or sensor-input fault, incompatible software, or gateway routing trouble.
Common causes
Most likely first.
- Module internal fault or sensor input drift
- Software version mismatch after replacement
- Gateway module routing CAN messages incorrectly
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
How to diagnose it
- Scan all modules and review freeze-frame data to identify the controller that logged U042C and any related suspension, chassis, or communication faults.
- Check for ride-height, damper, or vehicle-dynamics warnings and note any change in suspension behavior or handling.
- Inspect chassis control module B, its sensor connections, the gateway, and visible CAN wiring for damage, corrosion, loose connections, or water intrusion.
- Compare module B's live chassis data with the vehicle's observed state and check whether other codes identify a specific sensor input.
- Verify software compatibility and test module B inputs and CAN message routing against the manufacturer's procedures before replacing components.
Common fixes
- Repair loose, corroded, or damaged wiring or connectors serving chassis control module B.
- Repair a sensor input fault if testing shows it is making module B's data implausible.
- Correct incompatible software or configuration after a module replacement.
- Repair gateway routing or replace chassis control module B if testing confirms the fault is internal.
Can I keep driving?
Drive cautiously and avoid sharp maneuvers, heavy loads, and rough roads because chassis or suspension functions may be limited. If handling or ride height changes, or limp mode affects safe control, stop safely and arrange recovery.
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.