B133613 - B133613 Refrigerant Temperature Sensor 3 Open Circuit

meaning the sensor loop failed to form the expected voltage divider resistor network, causing Control Unit unable to accurately map current system thermal conditions, thereby cutting off the AC strategy calculation link based on thermodynamic models.

Common Fault Symptoms

After this DTC activates, drivers may perceive changes in vehicle operation status or instrument feedback in the following dimensions:

• AC cooling output capability limited, air outlet temperature fluctuation or unable to reach set value possible.
• Partial HVAC functions disabled, related control strategies enter limp home mode.
• Dashboard may display "Check Engine" or specific HVAC fault icon.
• On-board diagnostic system internally stores historical freeze frame data, but no audible or tactile noise apparent on user end.

Core Fault Cause Analysis

Based on technical logic dissection, fundamental reasons for triggering this DTC can be summarized into three physical dimensions:

1. Hardware Component Failure (Sensor Element) Refers to the sensing element of Refrigerant Temperature Sensor 3 itself experiencing open circuit damage. This typically manifests as resistance connection point breakage inside the sensor probe or thermistor characteristic drift to limit high resistance state, causing signal transmission path interruption. Additionally, if Right Domain Controller inside control unit has logical processing anomaly or power management module failure, it may misjudge as external open circuit.
2. Harness & Connector Involves harness integrity problems between sensor and control unit connection. Includes physical wire breakage due to insulation layer damage, pin retreat causing poor contact, or cable stress fatigue caused by high temperature refrigerant environment. Oxidation or loosening of connector internal contacts will cause electrical connection interruption, leading Control Unit reading abnormal high potential signal.
3. Controller Logic Analog front-end circuit inside Right Domain Controller may experience failure, unable to correctly sample sensor pin voltage, or generate offset in signal conditioning stage, thus incorrectly judging input as open circuit state.

Technical Monitoring and Trigger Logic

The generation of this DTC follows strict electrical threshold judgment algorithm, its trigger mechanism includes following technical elements:

• Monitoring Target: System real-time monitor Refrigerant Temperature Sensor 3 signal loop voltage level, specific parameter is Sensor Output Voltage Detected.
• Trigger Threshold: When instantaneous voltage value identified by control unit satisfies specific conditions, fault judgment starts. According to data stream definition, Set Fault Condition (Set Fault Condition) as: $4.95V < V_{sensor}$ (i.e., output voltage higher than $4.95V$). In typical sensor divider circuit, this high voltage threshold usually indicates ground loop open or power terminal direct connection state.
• Trigger Condition: Fault logic effective monitor and record data only when Ignition Switch in ON Position. This means system needs real-time self-check with ignition on, if signal not return to normal thermistor divider zone at this time, confirm permanent or intermittent open circuit fault.

Cause Analysis Based on technical logic dissection, fundamental reasons for triggering this DTC can be summarized into three physical dimensions:

1. Hardware Component Failure (Sensor Element) Refers to the sensing element of Refrigerant Temperature Sensor 3 itself experiencing open circuit damage. This typically manifests as resistance connection point breakage inside the sensor probe or thermistor characteristic drift to limit high resistance state, causing signal transmission path interruption. Additionally, if Right Domain Controller inside control unit has logical processing anomaly or power management module failure, it may misjudge as external open circuit.
2. Harness & Connector Involves harness integrity problems between sensor and control unit connection. Includes physical wire breakage due to insulation layer damage, pin retreat causing poor contact, or cable stress fatigue caused by high temperature refrigerant environment. Oxidation or loosening of connector internal contacts will cause electrical connection interruption, leading Control Unit reading abnormal high potential signal.
3. Controller Logic Analog front-end circuit inside Right Domain Controller may experience failure, unable to correctly sample sensor pin voltage, or generate offset in signal conditioning stage, thus incorrectly judging input as open circuit state.

Technical Monitoring and Trigger Logic

The generation of this DTC follows strict electrical threshold judgment algorithm, its trigger mechanism includes following technical elements:

• Monitoring Target: System real-time monitor Refrigerant Temperature Sensor 3 signal loop voltage level, specific parameter is Sensor Output Voltage Detected.
• Trigger Threshold: When instantaneous voltage value identified by control unit satisfies specific conditions, fault judgment starts. According to data stream definition, Set Fault Condition (Set Fault Condition) as: $4.95V < V_{sensor}$ (i.e., output voltage higher than $4.95V$). In typical sensor divider circuit, this high voltage threshold usually indicates ground loop open or power terminal direct connection state.
• Trigger Condition: Fault logic effective monitor and record data only when Ignition Switch in ON Position. This means system needs real-time self-check with ignition on, if signal not return to normal thermistor divider zone at this time, confirm permanent or intermittent open circuit fault.