B0821Right Headlamp High Beam Circuit
- Generic OBD-II code · Body
- How the car detects it
- For B0821 there is no public trace in J2012 extracts, factory manuals or NHTSA files. The title describes the right main-beam circuit. Saab's 9-3 (type 9440) watches it under its own number B3866: open (04) when the lamp draws under 0.8 A with main beam on, overcurrent (0B) in the 7.9–30 A band; apart from the warning the module takes no action. Because high beam is only used on empty roads, a one-sided failure is often noticed late, mostly as a darker right verge. In GM's 2011 Saab 9-5, by contrast, a fault on the shared relay line (B2580 01) switches off both sides together. FMVSS 108 lists the beam switching device and the upper-beam indicator as required equipment. Left side: B0820.
- What you may notice
- Right main beam stays dark, left one works
- Lamp warning in the display when high beam is switched on
- Likely causes
- LikelyRight high-beam bulb failed
- PossibleSupply wire to the right headlamp open or shorted
- PossibleHigher-wattage bulb fitted, triggering overcurrent
- RareMain-beam output of the lighting module faulty
- Repair
- Easy · Often possible to do yourself.Typical cost: €10 – €500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.