B0820Left Headlamp High Beam Circuit
- Generic OBD-II code · Body
- How the car detects it
- B0820 is undocumented: neither open J2012 material nor factory or NHTSA papers list it. The title refers to the left main-beam output. In the second-generation Saab 9-3 the front electrical centre flags B2580 04 when the left main beam draws under 0.8 A while switched on and B2580 0B for 7.9 to 30 A. GM's 2011 Saab 9-5 works differently: both main beams are fed through one relay whose coil the body control module grounds, and if that control line is shorted to battery plus, B2580 01 is stored with both high beams off. HELLA points out that bi-xenon units form low and high beam in one module by moving a shutter, so a fault can also sit in that mechanism. FMVSS 108 requires an upper-beam indicator for the driver. Right side: B0821.
- What you may notice
- Left main beam stays dark when high beam is selected
- Both main beams fail if the shared relay circuit is affected
- Lamp failure message in the display
- Likely causes
- LikelyLeft high-beam bulb burnt out
- PossibleHigh-beam relay or its control line faulty
- PossibleShutter actuator in a bi-xenon module stuck
- RareCorroded headlamp connector
- 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.