B0851Right Brake Lamp Circuit
- Generic OBD-II code · Body
- How the car detects it
- Published J2012 tables skip B0851, and service literature and NHTSA filings never cite it either. The title names the right stop-lamp circuit. The GM-developed Saab 9-3 tests this lamp whenever the brake light is on and stores B3878 04 once the right lamp draws less than 50 mA; the high-mounted lamp is judged separately under B3884 with a lower limit of 20 mA. If both sides and the third lamp go dark together, the cause usually lies upstream, at the brake light switch or a shared fuse, not in one lamp circuit. For today's networked rear lamps HELLA names failed LED segments and faulty plugs as typical findings. FMVSS 108 requires working stop lamps on every car. Repair without delay; left side: B0850.
- What you may notice
- Right brake light dark while the left one and the third lamp work
- Brake light warning in the display
- Reduced braking signal to following drivers; repair at once
- Likely causes
- LikelyRight stop-lamp bulb or LED segment failed
- PossibleLoose or corroded plug at the right tail lamp
- PossibleWire to the right tail lamp broken
- RareLamp driver in the rear module faulty
- Repair
- Easy · Often possible to do yourself.Typical cost: €5 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.