Right Rear Fog Light Circuit Malfunction
The B0091 code means the vehicle's onboard diagnostic system has detected: Right Rear Fog Light Circuit Malfunction. This is a low severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- easy
- Estimated cost
- $10 - $150 (parts and labor)
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Common Symptoms
- Right rear fog light not illuminating
- Rear fog indicator on but light not working
- Reduced rear fog visibility
- Failed rear fog light inspection
Probable Causes (Ranked by Likelihood)
- Burned out rear fog light bulb Very High
- Corroded rear fog socket High
- Damaged wiring to rear fog Moderate
- Rear fog relay failure Low
Step-by-Step Diagnostic Procedure
-
Inspect rear fog bulb
-
Check socket for corrosion
-
Test voltage at connector
-
Check relay and fuse
Frequently Asked Questions
When should I use rear fog lights?
Only in severely reduced visibility such as dense fog or heavy rain.
Can I add rear fog lights?
Aftermarket kits are available with a dedicated switch.
Will this affect tail or brake lights?
No, the rear fog light is on a separate circuit.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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