B133413 - B133413 Refrigerant Temperature Sensor 2 Open Circuit

B133413 Refrigerant Temperature Sensor 2 Open Circuit Technical Analysis

### H3 Fault Depth Definition

B133413 as a vehicle diagnostic trouble code (DTC), defines distinct circuit state abnormalities in the Body Control Network (typically associated with the Left Domain Controller). This fault code specifically points to the electrical pathway integrity failure of the "Refrigerant Temperature Sensor 2", i.e., the system judges it as an "Open Circuit" (Open Circuit). In the automotive thermal management system, the refrigerant temperature sensor plays a key feedback role, providing real-time evaporator or condenser pipe temperature data to the control unit for calculation in compressor operation logic. When the diagnostic system detects circuit signal voltage deviating from the normal voltage divider range and exceeding the high threshold, the system judges this loop is in a physical disconnection or high impedance state, thus recording this fault code to prompt the driver and repair engineers.

### H3 Common Fault Symptoms

After the vehicle control unit detects the above abnormal signals, it restricts the operation of related functions to protect system safety and prevent compressor overheating or pressure abnormalities. Based on original data "Partial HVAC System Function Failure", specific phenomena that owners may observe or perceive during daily driving include:

• Automatic AC mode cannot properly regulate cabin temperature to the set value;
• Air conditioning cooling efficiency drops or completely loses cooling ability;
• The HVAC system fault indicator light on the instrument panel may turn on;
• Cabin occupants feel insufficient airflow or delayed temperature control response under specific conditions.

### H3 Core Fault Cause Analysis

Regarding the determination of B133413 fault code, technically it is mainly attributed to hardware or logic anomalies in three dimensions:

1. Sensor Component (Hardware Failure): The thermistor element inside Refrigerant Temperature Sensor 2 may have suffered permanent open circuit damage, resulting in inability to divide voltage or output normal signals.
2. Wiring Harness & Connectors (Physical Connection): Wires between the control unit and sensor appear broken, pins withdrawn from sockets, or connector terminals exist oxidation, loose connection physical damage, causing circuit disconnection in specific areas.
3. Controller Logic (Calculation Unit): The ADC module responsible for monitoring signal input or related power management circuits inside the Left Domain Controller may have anomalies, leading to inability to correctly identify input impedance or false voltage values reported.

### H3 Technical Monitoring & Trigger Logic

The setting and triggering of this fault code follows strict electrical threshold logic to minimize false positives. Diagnostic programs only start verification processes under specific static or dynamic conditions:

• Signal Monitoring Target: System real-time monitors the analog voltage signal output by Refrigerant Temperature Sensor 2.
• Trigger Condition (Ignition Status): Fault determination must be made with ignition switch in ON position, to ensure control unit power is normal and circuit is activated.
• Setting Threshold (Voltage Threshold): When sensor output voltage continuously exceeds $4.95V$, the control unit judges it as "Open Circuit" state.

In standard temperature sensor voltage divider circuits, normal working voltage usually below threshold, once signal voltage breaks through $4.95V$ upper limit boundary, and this voltage value fits open circuit characteristics (e.g., close to reference voltage or unloaded high level), system immediately generates B133413 fault code and stores into non-volatile memory. This logic ensures warning mechanism is only activated when circuit physically disconnected or high impedance open circuit exists.