Car AC & Climate Control OBD-II Fault Code Lookup
Did your OBD-II scanner throw cryptic climate control codes? Auto Save provides a comprehensive technical database for diagnosing AC faults across Toyota, Lexus, Nissan, Ford, and GM vehicles, helping you differentiate harmless shadow readings from real mechanical failures.
Search HVAC Trouble Codes (B-Codes & P-Codes)
Enter your OBD-II scan code (e.g., B1421 or P0532) or select a category below to decode symptoms and verify false alarms.
Code B1421 - Solar Sensor Circuit (Passenger Side) - Toyota / Lexus
Code B1421 in Toyota and Lexus vehicles indicates that the passenger-side solar sensor is not detecting direct sunlight or has a circuit abnormality.
Code B1424 - Solar Sensor Circuit (Driver Side) - Toyota / Lexus
The companion code to B1421 in dual-zone climate Toyota and Lexus vehicles, measuring solar load on the driver cabin zone.
Code B1422 - Compressor Lock Sensor Circuit (Toyota / Lexus)
A critical code indicating that the A/C ECU detected a speed difference between the engine crank pulley and compressor shaft, meaning the compressor is slipping or locked to protect the serpentine belt.
Code B1423 - Pressure Sensor Circuit / Refrigerant Abnormal (Toyota / Lexus)
Code B1423 indicates that refrigerant pressure is outside safe operating thresholds (either critically low due to freon leak, or dangerously high due to condenser blockage or overcharge).
Code B1412 - Ambient Temperature Sensor Circuit (Toyota / Lexus)
Indicates an open, short, or out-of-range signal in the ambient air temperature sensor circuit behind the front grille.
Code B1413 - Evaporator Temperature Sensor Circuit (Toyota / Lexus)
Monitors the surface temperature of the indoor evaporator core to prevent moisture freezing into ice. A fault disrupts compressor regulation.
Code B1441 - Air Mix Door Motor Circuit (Toyota / Lexus)
Indicates an electrical or mechanical fault in the blend door servo motor that modulates hot and cold air mixing.
Code B1442 - Air Inlet Door Motor Circuit (Toyota / Lexus)
Fault in the actuator controlling the fresh air vs recirculated air intake flap.
Code P0530 - A/C Refrigerant Pressure Sensor Circuit Malfunction
A generic OBD-II powertrain code indicating the PCM receives an implausible or erratic voltage signal from the A/C refrigerant pressure transducer.
Code P0531 - A/C Refrigerant Pressure Sensor Circuit Range/Performance
PCM detected an erratic pressure reading or pressure that failed to change when the compressor engaged.
Code P0532 - A/C Refrigerant Pressure Sensor Circuit Low Input
Indicates sensor output voltage dropped below threshold (< 0.2V), interpreted by ECU as total freon loss or broken circuit.
Code P0533 - A/C Refrigerant Pressure Sensor Circuit High Input
Indicates sensor signal exceeded maximum safe voltage (> 4.8V), representing extreme dangerous pressure or a 12V short-to-power.
Code P0645 - A/C Clutch Relay Control Circuit Malfunction
PCM detected an open circuit, short, or impedance failure in the control circuit of the A/C compressor clutch relay.
Code P0480 - Cooling Fan 1 Control Circuit Malfunction
Indicates a circuit malfunction in the primary engine cooling fan, responsible for drawing airflow across the AC condenser.
Code B10A2 - Refrigerant Pressure Sensor Signal Failure (Nissan / Ford)
Specific code for Nissan, Infiniti, and Ford indicating the BCM/HVAC controller is receiving an invalid refrigerant pressure reading.
Code B1443 - Air Outlet Damper / Mode Door Motor Circuit (Toyota / Lexus)
Indicates a failure in the actuator that directs airflow between face vents, footwells, and windshield defroster.
Code P0534 - A/C Refrigerant Charge Loss Condition
PCM monitors pressure rate-of-change and detected an unexpected pressure drop during compressor operation, indicating a refrigerant leak.
Code P0646 - A/C Clutch Relay Control Circuit Low
Indicates PCM detected a short-to-ground condition in the A/C clutch relay control coil circuit.
Code P0647 - A/C Clutch Relay Control Circuit High
Indicates an open circuit or short-to-voltage condition in the A/C clutch relay control circuit.
Code B1245 - Blend Door Actuator Potentiometer Circuit (Ford / GM)
Common in Ford and GM trucks/SUVs, indicating failed feedback potentiometer inside the temperature blend actuator.
Code B1400 - HVAC Control Module Communication / Internal Error
Indicates communication loss or internal memory/microprocessor error in the A/C amplifier or climate control module.
No matching fault code found
Did you get a different code? Send a screenshot of your scanner to Auto Save technicians on WhatsApp for a free interpretation.
Ask an Auto Save Mechanic via WhatsAppKey Facts Before Scanning Your Car AC System
Many drivers waste hundreds of riyals replacing healthy sensors because generic repair shops misinterpret shadow readings. Keep these rules in mind:
The Solar Sensor Trap (B1421 / B1424)
In Toyota and Lexus models, the solar sensor requires direct high-lux daylight to register. Scanning inside an indoor workshop or shaded bay always triggers B1421 as an active code, which is 100% normal.
P-Codes vs. B-Codes
P-Codes illuminate the Check Engine light and protect the compressor from dry seizure. B-Codes originate from the climate amplifier and govern blend actuators, temperature doors, and cabin sensors.
Dashboard Clicking Is Not Freon
Trouble codes like B1441 or B1245 indicate stripped plastic gears inside the blend door actuator. Topping off refrigerant will never solve temperature split problems.
Frequently Asked Questions About Car AC Trouble Codes
Expert insights from Auto Save automotive air conditioning specialists in Riyadh
Does Toyota / Lexus trouble code B1421 mean my AC is broken?
Not at all! In 95% of cases, code B1421 simply indicates the vehicle was scanned indoors inside a workshop, under a shaded canopy, or at night. The passenger dashboard solar sensor requires direct sunlight to register and clear. If your AC blows cold air, never pay to replace this sensor!
What is the difference between P-Codes and B-Codes in automotive AC systems?
P-Codes (Powertrain) are managed by the engine control unit (PCM/ECM) and oversee critical safety items like refrigerant pressure transducers and compressor clutch cutoff (e.g., P0530, P0532). B-Codes (Body) are handled by the climate control amplifier and govern interior comfort, air mix actuators, and cabin solar sensors (e.g., B1421, B1441).
How do you trigger Toyota & Lexus self-diagnosis without an OBD scanner?
Turn the ignition switch OFF. Hold down both the AUTO and RECIRCULATION buttons simultaneously on the climate control panel, then turn the ignition ON (engine off). The panel lights will blink and automatically flash two-digit DTC fault codes on the digital temperature display.
Why is the A/C button light flashing in Toyota vehicles?
A flashing A/C light is an urgent alert indicating trouble code B1422 (Compressor Revolution / Lock Sensor). The ECU detected a speed difference between the engine crank pulley and compressor hub and automatically disengaged the compressor clutch to prevent belt snap.