What it means
A control module received invalid data from battery charger control module A. The code identifies a data validity fault; the specific affected function depends on the vehicle.
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
Battery charger control module A manages and reports charging-system operation to other modules over the vehicle network. U049C sets when a receiving module judges the data from charger module A invalid, which can limit or disable charging functions depending on the vehicle.
Common causes
Most likely first.
- Fault in the transmitting module
- Network wiring or connector fault
- Module power or ground fault
- Software or configuration mismatch
Symptoms
- Charging functions may be limited or unavailable
- Related communication codes or charging-system warnings may appear
How to diagnose it
- Use a scan tool to save freeze-frame data and check for other charging or high-voltage system codes before clearing anything.
- Check whether U049C returns and review charging-system status data, since a current fault may be limiting charging.
- Inspect charger module A connectors and network wiring for looseness, corrosion, damage, or chafing without disturbing high-voltage components.
- Check the module's low-voltage power and ground using the manufacturer's procedure; leave high-voltage circuit checks to qualified personnel.
- If wiring and supplies are sound, use vehicle-specific diagnostics to assess charger module A and confirm software and configuration.
Common fixes
- Reconnect or clean a loose or corroded low-voltage connector at charger module A.
- Repair damaged network wiring to charger module A.
- Repair a poor module power or ground connection.
- Apply the correct software update or configuration if specified for the vehicle.
- Replace battery charger control module A if testing confirms it is faulty.
Can I keep driving?
Charging may be limited or unavailable, and the vehicle could lose usable battery charge or enter a restricted operating mode. Avoid relying on the vehicle for a long trip; arrange prompt diagnosis, especially if a charging warning 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.