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DTC codes / B08xx · Airbags, seats, doors, lights and comfort systems / B0841

B0841Right Rear Turn Signal Circuit

B0841 indicates that the body control module (BCM) has detected an open circuit, short to ground, or short to voltage in the right rear turn signal circuit. The BCM commands the right rear turn signal on and monitors the circuit for expected current flow; when the feedback does not match the command, it stores this code and may disable the output.

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

Symptoms you may notice

  • Right rear turn signal does not illuminate when activated
  • Turn signal flashes rapidly (hyperflash) on the right side
  • Turn signal indicator on the instrument cluster flashes faster than normal
  • Often no symptoms besides the warning light if the fault is intermittent
  • Right rear turn signal may glow dimly or stay on constantly
  • Rear turn signal may work intermittently depending on temperature or vibration

Common causes, most likely first

  1. Failed right rear turn signal bulb (filament open or LED assembly failure)
  2. Corroded, loose, or damaged bulb socket contacts
  3. Open or shorted wiring between the BCM and the right rear turn signal
  4. Damaged connector pins at the BCM or at the rear lamp assembly
  5. Failed body control module (BCM) output driver
  6. Aftermarket LED bulb or incorrect bulb type causing current mismatch
  7. Water intrusion into the rear lamp housing or connector

How to diagnose and fix it

  1. Verify the right rear turn signal bulb is correct, seated properly, and not burned out; replace if faulty
  2. Inspect the bulb socket and connector for corrosion, burning, or loose pins; clean or repair as needed
  3. Check the turn signal fuse and relay if applicable to the circuit
  4. Disconnect the BCM and rear lamp connector, then measure resistance and voltage on the right rear turn signal circuit to locate opens or shorts
  5. Wiggle-test the harness while monitoring the circuit to find intermittent faults
  6. If wiring and components are good, substitute a known-good BCM or perform bidirectional control tests to confirm BCM output failure
  7. Clear the code and retest the turn signal operation to confirm the repair

Why the BCM flags this circuit

  • The BCM often sets B0841 when an aftermarket LED bulb is installed because the lower current draw mimics an open circuit, even though the bulb lights normally.
  • A poor ground at the rear lamp assembly can cause the BCM to see unexpected voltage on the turn signal circuit and set this code, so always check grounds before condemning the module.
  • Intermittent B0841 codes are frequently caused by a chafed wire in the trunk hinge area or near a body seam where the harness flexes.
  • Some vehicles use the same circuit for both turn and brake functions, so a brake light complaint may accompany this code even though the definition only mentions turn signal.
  • The BCM may disable the right rear turn signal output entirely after setting this code, so the lamp may not work even if the bulb is good until the code is cleared.

Can I keep driving with B0841?

You can generally drive safely with B0841 because the right rear turn signal is not a critical safety system, but other drivers may not see your intended turn. Avoid driving at night or in heavy traffic until repaired, and use hand signals if the turn signal is completely inoperative.

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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