Failed tail lamp bulb or LED assembly (most common).; Corroded, loose, or damaged bulb socket or connector at the tail lamp housing.; Broken, chafed, or shorted wire in the rear tail lamp circuit, often near the trunk hinge or grommet.; Blown fuse or faulty relay dedicated to the tail lamp circuit (though some vehicles use solid-state drivers).; Water intrusion into the tail lamp housing or connector, causing corrosion or shorting.; Faulty body control module (BCM) or rear electronic module, though rare.

DTC codes / B02xx · Airbags, seats, doors, lights and comfort systems / B0233

B0233Rear Tail Lamp Circuit

Q: What does code B0233 mean?

Rear Tail Lamp Circuit. B0233 indicates that the body control module (BCM) has detected an abnormal condition in the rear tail lamp circuit, typically an open circuit, short to ground, or short to voltage. The BCM monitors the circuit and sets this code when the current or voltage falls outside the expected range for proper tail lamp operation.

B0233 indicates that the body control module (BCM) has detected an abnormal condition in the rear tail lamp circuit, typically an open circuit, short to ground, or short to voltage. The BCM monitors the circuit and sets this code when the current or voltage falls outside the expected range for proper tail lamp operation.

SystemBody

Code typeGeneric (all makes)

SeverityLow

Fix difficultyIntermediate

AreaAirbags, seats, doors, lights and comfort systems

Symptoms you may notice

The tail lamps may not illuminate when the headlights are switched on.
One or both rear tail lamps may be dimmer than normal or flicker intermittently.
The dashboard may display a warning message such as 'Check Rear Tail Lamp' or a bulb-out indicator.
Often no symptoms besides the warning light, especially if the fault is intermittent.
Other rear lighting functions (brake, turn, reverse) may still work normally, depending on the circuit design.

Common causes, most likely first

Failed tail lamp bulb or LED assembly (most common).
Corroded, loose, or damaged bulb socket or connector at the tail lamp housing.
Broken, chafed, or shorted wire in the rear tail lamp circuit, often near the trunk hinge or grommet.
Blown fuse or faulty relay dedicated to the tail lamp circuit (though some vehicles use solid-state drivers).
Water intrusion into the tail lamp housing or connector, causing corrosion or shorting.
Faulty body control module (BCM) or rear electronic module, though rare.

How to diagnose and fix it

Verify the complaint and check all rear tail lamp bulbs and LED assemblies for proper operation.
Inspect the bulb sockets and connectors for corrosion, loose pins, or damage; clean or replace as needed.
Check the tail lamp fuse and relay (if applicable) and replace if faulty.
Perform a voltage drop test on the ground circuit and check for power at the tail lamp connector with the lights on.
Trace the wiring harness from the BCM to the tail lamps, looking for chafed, pinched, or broken wires, especially at flex points.
If wiring and components are good, test the BCM output with a scan tool or oscilloscope; replace the BCM only after confirming all other possibilities.
Clear the code and verify the repair by cycling the lights and test-driving.

Common Misdiagnosis Traps for B0233

A bulb that looks good can still be faulty; always test with a known-good bulb or measure resistance.
Corrosion inside a connector can cause intermittent faults that don't appear during a quick visual check; disassemble and inspect carefully.
The BCM may set this code even if the tail lamps work, due to a brief short or open that occurs only under vibration or temperature changes.
Aftermarket LED bulbs or improper modifications are a frequent cause of circuit faults because they draw different current than the BCM expects.
The tail lamp circuit often shares a ground with other rear lighting; a bad ground can cause multiple lighting issues and set related codes.

Can I keep driving with B0233?

It is generally safe to drive with this code, but be aware that the rear tail lamps may not function, reducing visibility to other drivers. Avoid driving at night or in low-visibility conditions until repaired, and check local regulations regarding lighting equipment.

Tools that help

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