U048B: Invalid Data Received From Headlamp Leveling Control Module B

What it means

A control module received invalid data from headlamp leveling control module B. 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

How it works

Headlamp leveling control module B controls or reports the position adjustment of the B-side headlamp system, depending on vehicle design. U048B sets when another module rejects data from that controller as invalid, which can prevent correct headlamp leveling.

Common causes

Most likely first.

1. Fault in the transmitting module
2. Network wiring or connector fault
3. Module power or ground fault
4. Software or configuration mismatch

Symptoms

• Headlamp leveling may not work correctly
• Lighting warning or related communication codes may appear

How to diagnose it

1. Scan all modules and save freeze-frame details, checking for headlamp, suspension-height sensor, lighting, and network codes alongside U048B.
2. With the vehicle safely parked, compare the apparent aim and leveling response of the B-side headlamp with the other side, without looking directly into the beam.
3. Inspect module B’s connector, nearby harness, and any associated leveling sensor linkage for damage, looseness, corrosion, or signs of water entry.
4. Check module B’s power and ground and inspect its network wiring using the manufacturer’s procedure.
5. Use a vehicle-capable scan tool to compare module B’s reported position or status with other modules’ data, and check for calibration, software, or configuration issues after repairs.
6. If wiring and configuration are sound, follow the manufacturer’s diagnostic procedure to determine whether module B or network routing is sending invalid data.

Common fixes

• Repair a loose, corroded, or damaged connector or harness at headlamp leveling module B.
• Repair damaged or disconnected leveling sensor linkage identified during inspection.
• Restore module B’s power or ground, or correct its network wiring fault.
• Complete the required calibration or software configuration after module replacement.
• Replace module B or repair the gateway only if testing confirms the fault source.

Can I keep driving?

Avoid night driving or driving in poor visibility if the B-side headlamp aim is visibly wrong, since it can reduce your view or dazzle other drivers. Have the lighting fault addressed promptly; a check-engine light may also be present, but this code alone does not indicate an emissions fault.