Code Definition

B0198 — Solar Sensor Circuit Low

System: Body  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About B0198

B0198 is a generic (obd-ii standard) body diagnostic trouble code. It belongs to the B-prefix family of codes, which covers body, interior, airbag, or comfort-electronics faults.

When B0198 is stored, the module has detected a signal or supply voltage lower than the expected operating range; and a sensor-related fault — the reported value from the named sensor is out of spec.

Scanning & clearing: Body (B) codes are often stored in the body control module, airbag module, or climate module. A basic OBD-II tool usually will not read body codes — an enhanced or OEM-level scan tool is typically required.

Because B0198 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

The solar (sunload) sensor is a small photodiode-based sensor mounted on top of the dashboard, normally near the defrost vents or A-pillar, where it has an unobstructed view of the sky. It supplies the HVAC control module with a varying voltage or digital signal that represents incoming solar radiation, and the module uses this information to compensate automatic climate control for radiant heat entering the cabin — raising blower speed, biasing airflow to the sunlit side, and holding the A/C compressor on a little longer on bright days. DTC B0198 is set when the HVAC module sees the signal ...

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