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DTC codes / B08xx · Airbags, seats, doors, lights and comfort systems / B0811

B0811Right Headlamp Low Beam Circuit

B0811 is a body code indicating that the body control module (BCM) has detected an abnormal condition in the right headlamp low beam circuit, such as an open circuit, short to ground, or excessive current draw. The BCM monitors the voltage and current on the control circuit and sets this code when the feedback does not match the commanded state.

SystemBody
Code typeGeneric (all makes)
SeverityLow
Fix difficultyIntermediate
AreaAirbags, seats, doors, lights and comfort systems

Symptoms you may notice

  • The right low beam headlamp does not illuminate when switched on.
  • The right low beam may flicker or intermittently work.
  • A warning light or message on the dashboard indicating a lamp fault.
  • Often no symptoms besides the warning light if the fault is intermittent.
  • Other lights on the same circuit (e.g., parking lamps) may also be affected in some vehicles.
  • The left low beam may continue to operate normally, making the fault less obvious at night.

Common causes, most likely first

  1. Failed right low beam bulb (most common).
  2. Corroded, loose, or damaged right headlamp connector or bulb socket.
  3. Open or shorted wire in the right low beam circuit (e.g., chafed harness, broken wire).
  4. Blown fuse or faulty relay dedicated to the right low beam (if equipped).
  5. Faulty body control module (BCM) or headlamp control module.
  6. Water intrusion into the headlamp assembly or connector causing corrosion.
  7. Aftermarket LED or HID bulb installation causing incompatible current draw.

How to diagnose and fix it

  1. Verify the right low beam bulb is not burned out by swapping it with the left side or inspecting the filament.
  2. Inspect the right headlamp connector and bulb socket for corrosion, melting, or loose pins; clean or repair as needed.
  3. Check the fuse and relay (if applicable) for the right low beam circuit and replace if faulty.
  4. Measure voltage and resistance on the right low beam control circuit at the headlamp connector to identify opens or shorts.
  5. Inspect the wiring harness from the BCM to the headlamp for damage, especially near moving components or heat sources.
  6. If the circuit tests good, check for BCM software updates or perform a BCM diagnostic test to confirm internal failure.
  7. Replace the BCM only after all other causes are ruled out and proper programming is available.

Before you replace the body control module

  • A common oversight is replacing the BCM when the real problem is a corroded ground connection for the right headlamp, which can mimic a circuit fault.
  • Aftermarket LED or HID bulbs often draw different current than the BCM expects, setting a false B0811 even though the lamp works.
  • The BCM may set B0811 if the right low beam circuit is shorted to the parking lamp circuit, so inspect for melted wires in the headlamp assembly.
  • On some vehicles, the right low beam is controlled by a separate module (e.g., headlamp control module) that communicates with the BCM, so a fault there can set B0811.
  • Intermittent B0811 codes often result from a loose ground wire at the radiator support or inner fender, which is easy to miss during visual inspection.

Can I keep driving with B0811?

You can usually drive safely during daylight, but avoid nighttime driving until the fault is repaired because the right low beam may be inoperative. If both low beams are out, do not drive at night.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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