B0156Sun Load Sensor Circuit
- Generic OBD-II code · Body
- How the car detects it
- The publicly available J2012 lists skip B0156, and public carmaker documents do not mention it; the same meaning is covered by code B0305. A sun load sensor on top of the dashboard tells automatic climate control how strongly sunlight heats the cabin, so the system can add cooling early. HELLA's solar sensor sits centrally on the dash, measures radiation across different zones and reports over LIN. Patent US6888120B2 uses two light-collecting lenses, each aimed at its own photodiode, to separate driver and passenger sides. GM files this sensor under B0183 instead: in the 2011 Saab 9-5 the HVAC module sets it when the 5 V identifying pulse fails to arrive and then works with zero sun intensity.
- What you may notice
- Cabin gets too warm in strong sun because the system does not add cooling
- Automatic blower and temperature react only to air temperature
- Likely causes
- LikelySensor plug under the dash top cover loose or damaged after windscreen work
- PossiblePhotodiode or electronics in the sun load sensor failed
- RareSignal or supply wire shorted or open behind the dashboard
- Repair
- Medium · Often possible to do yourself.Typical cost: €30 – €200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.