OBD2 B1259: Solar Radiation Sensor Open Circuit
The B1259 code indicates an open circuit in the solar radiation sensor circuit. This sensor measures the intensity of sunlight entering the cabin and sends a voltage signal to the HVAC control module, which adjusts the automatic climate control settings to compensate for solar heating. An open circuit means the control module detects an electrical break in the sensor wiring, connector, or the sensor itself, preventing the signal from reaching the module.
1. Commonly Affected Makes
2. Most Common Causes
- Faulty solar radiation sensor with internal open circuit
- Broken, cut, or interrupted wiring in the sensor circuit
- Corroded, bent, or disconnected sensor connector
- Short to ground in the sensor signal circuit
- Faulty HVAC control module (rare)
3. Symptoms You Will Notice
- Automatic climate control may not adjust properly for sunlight
- Possible HVAC system malfunction or reduced performance
4. Step-by-Step Diagnosis
Check for technical service bulletins (TSBs) related to the code
Visually inspect the solar radiation sensor and its wiring for damage
Test the sensor's voltage and resistance according to manufacturer specifications
Check for continuity and shorts in the sensor circuit
If all else fails, test or replace the HVAC control module
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, the vehicle is safe to drive. The main impact is on automatic climate control performance, which may not adjust for sunlight, but manual HVAC operation should still work.
How much does it cost to fix?▼
Repair costs typically range from $100 to $300, depending on the cause. A sensor replacement is usually $50-$150 for parts and $50-$150 for labor. Wiring repairs may cost less.