The B1317 diagnostic trouble code (DTC) indicates a problem with the in-car air temperature sensor circuit within a vehicle's Heating, Ventilation, and Air Conditioning (HVAC) system. This sensor plays a crucial role in maintaining cabin comfort by providing temperature data to the HVAC control module, enabling it to regulate heating and cooling functions effectively. When the B1317 code appears, it signals that the sensor's signal is either out of range (too high or too low) or completely absent, potentially leading to inaccurate temperature control and discomfort for the vehicle's occupants.
The proper functioning of the in-car air temperature sensor is essential for optimal HVAC performance. Without accurate temperature readings, the system may struggle to maintain the desired cabin temperature, resulting in either excessive heating or cooling. Addressing the B1317 code promptly can restore proper HVAC functionality, ensuring a comfortable and efficient driving experience.
| Attribute | Description | Possible Causes |
|---|---|---|
| Sensor Function | Measures the air temperature inside the vehicle cabin. This data is used by the HVAC control module to adjust heating, cooling, and ventilation. The sensor is usually a thermistor, a resistor whose resistance changes with temperature. | N/A |
| Diagnostic Trouble Code (DTC) B1317 Definition | "In Car Temperature Sensor Circuit Fault." Indicates that the HVAC control module has detected an issue with the in-car temperature sensor circuit, such as an open circuit, short circuit, or a signal that is outside of the expected range. | Open or short circuit in the sensor wiring: Damaged or corroded wires, loose connections. Faulty in-car temperature sensor: The sensor itself is defective and providing inaccurate readings or no reading at all. Faulty HVAC control module: The control module is malfunctioning and misinterpreting the sensor signal or unable to read it. Obstructed sensor: Dust or debris blocking airflow to the sensor. |
| Symptoms | Inaccurate cabin temperature control, HVAC system blowing hot or cold air regardless of settings, HVAC system not responding to temperature adjustments, DTC B1317 stored in the vehicle's computer, HVAC system operating intermittently. | N/A |
| Location | Typically located near the dashboard, often integrated into the overhead console, center console, or behind a small grille in the dashboard. The exact location varies depending on the vehicle make and model. | N/A |
| Sensor Type | Usually a thermistor, but can also be a solid-state temperature sensor. Thermistor resistance decreases as temperature increases (Negative Temperature Coefficient - NTC) in most automotive applications. | N/A |
| Testing Procedure | Visual inspection of the sensor and wiring for damage. Using a multimeter to check the sensor's resistance and compare it to the manufacturer's specifications. Testing the wiring for continuity and shorts to ground or voltage. Checking the voltage at the sensor connector. Scanning the HVAC control module for other DTCs. | N/A |
| Common Vehicle Brands Affected | This code is generic and can affect a wide range of vehicle makes and models, including but not limited to Ford, GM, Chrysler, Toyota, Honda, Nissan, and European brands like BMW, Mercedes-Benz, and Audi. Specific diagnostic and repair procedures may vary depending on the vehicle's make and model. | N/A |
| Troubleshooting Steps | 1. Visual Inspection: Check the sensor and its wiring for any signs of damage, corrosion, or loose connections. 2. Sensor Resistance Test: Use a multimeter to measure the sensor's resistance and compare it to the manufacturer's specifications. 3. Wiring Continuity Test: Check the wiring between the sensor and the HVAC control module for continuity. 4. Voltage Test: Check the voltage at the sensor connector to ensure that the sensor is receiving power. 5. Scan for Other DTCs: Use a scan tool to check for any other DTCs that may be related to the HVAC system. 6. HVAC Control Module Test: If all other tests pass, the HVAC control module may be faulty. | N/A |
| Repair Solutions | Repairing or replacing damaged wiring. Replacing the faulty in-car temperature sensor. Replacing the faulty HVAC control module (requires programming in some cases). Cleaning any obstructions blocking airflow to the sensor. | N/A |
| Related DTCs | Other HVAC-related DTCs that may indicate a problem with the system, such as codes related to the blend door actuator, refrigerant pressure sensor, or other temperature sensors. Addressing these codes may be necessary to resolve the B1317 issue. | N/A |
| Data Stream Parameters | When using a scan tool, relevant data stream parameters to monitor include: In-Car Temperature Sensor Reading (displayed in degrees Celsius or Fahrenheit), HVAC Control Module Temperature Request, Blend Door Position, and Refrigerant Pressure. Monitoring these parameters can help diagnose the root cause of the B1317 code. | N/A |
| Impact on Vehicle Performance | Primarily affects the comfort and efficiency of the HVAC system. Inaccurate temperature control can lead to discomfort for the vehicle's occupants. May also affect fuel economy if the HVAC system is constantly working harder than necessary to maintain the desired temperature. | N/A |
| Complexity of Repair | Varies depending on the root cause of the problem. Replacing a faulty sensor or repairing damaged wiring is typically a relatively straightforward repair. Replacing the HVAC control module can be more complex, as it may require programming and specialized tools. | N/A |
Detailed Explanations
Sensor Function: The in-car air temperature sensor acts as the HVAC system's "thermometer." It constantly monitors the air temperature inside the vehicle cabin and sends this information to the HVAC control module. This module uses this temperature data, along with other sensor inputs (like outside air temperature and coolant temperature), to determine the optimal settings for the heating, cooling, and ventilation systems. The sensor's accuracy is paramount for maintaining the desired cabin temperature and ensuring passenger comfort. It usually operates on a 5V circuit, providing a variable voltage signal back to the HVAC controller, proportional to the measured temperature.
Diagnostic Trouble Code (DTC) B1317 Definition: The B1317 code is a signal from the vehicle's onboard diagnostic system that the HVAC control module has detected a fault within the in-car temperature sensor circuit. This fault could be an open circuit (broken wire), a short circuit (wire touching ground or another wire), or a signal that is outside of the acceptable range. The HVAC control module constantly monitors the sensor's signal and compares it to expected values. If the signal deviates significantly from these expectations, the B1317 code is triggered and stored in the vehicle's computer.
Symptoms: The symptoms associated with the B1317 code can vary depending on the severity of the problem. Common symptoms include inaccurate cabin temperature control, where the HVAC system blows hot or cold air regardless of the temperature settings. The system may also fail to respond to temperature adjustments, or operate intermittently. The presence of the B1317 code itself is a key symptom, and a scan tool is required to retrieve it. In some cases, the HVAC system may default to a specific setting (e.g., full heat or full cool) as a safety measure.
Location: The location of the in-car air temperature sensor can vary depending on the vehicle's make and model. However, it is typically found near the dashboard, often integrated into the overhead console, center console, or behind a small grille in the dashboard. The grille allows air to circulate around the sensor, ensuring accurate temperature readings. Consulting the vehicle's repair manual or a wiring diagram is the best way to pinpoint the sensor's exact location. Accessing the sensor may require removing trim panels or other components.
Sensor Type: The most common type of in-car air temperature sensor is a thermistor. A thermistor is a resistor whose resistance changes with temperature. In most automotive applications, Negative Temperature Coefficient (NTC) thermistors are used, meaning that the resistance decreases as the temperature increases. The HVAC control module monitors the resistance of the thermistor to determine the cabin temperature. Solid-state temperature sensors are also used in some vehicles, offering higher accuracy and reliability.
Testing Procedure: Testing the in-car air temperature sensor involves a series of steps to isolate the problem. Start with a visual inspection of the sensor and wiring for any signs of damage or corrosion. Next, use a multimeter to check the sensor's resistance at various temperatures. Compare these readings to the manufacturer's specifications to determine if the sensor is functioning correctly. Continuity testing the wiring ensures that there are no breaks in the circuit. Voltage testing confirms that the sensor is receiving the correct voltage from the HVAC control module. Finally, use a scan tool to check for any other DTCs that may be related to the HVAC system.
Common Vehicle Brands Affected: The B1317 code is a generic code, meaning that it can affect a wide range of vehicle makes and models. While specific diagnostic and repair procedures may vary depending on the vehicle, the underlying principles remain the same. Common brands affected include Ford, GM, Chrysler, Toyota, Honda, Nissan, and European brands like BMW, Mercedes-Benz, and Audi. Always consult the vehicle's repair manual for specific instructions.
Troubleshooting Steps:
- Visual Inspection: Thoroughly inspect the sensor and its wiring for any signs of damage, corrosion, or loose connections. Pay close attention to the connector and wiring harness.
- Sensor Resistance Test: Use a multimeter to measure the sensor's resistance and compare it to the manufacturer's specifications. This test is best performed at different temperatures to assess the sensor's accuracy.
- Wiring Continuity Test: Check the wiring between the sensor and the HVAC control module for continuity. This ensures that there are no breaks in the circuit.
- Voltage Test: Check the voltage at the sensor connector to ensure that the sensor is receiving power. A typical reading should be around 5 volts.
- Scan for Other DTCs: Use a scan tool to check for any other DTCs that may be related to the HVAC system. Addressing these codes may be necessary to resolve the B1317 issue.
- HVAC Control Module Test: If all other tests pass, the HVAC control module may be faulty. This is a less common cause, but it should be considered if all other possibilities have been ruled out.
Repair Solutions: Repair solutions for the B1317 code depend on the root cause of the problem. If the wiring is damaged, repairing or replacing the wiring is necessary. A faulty in-car temperature sensor should be replaced with a new one. If the HVAC control module is faulty, it may need to be replaced and programmed. If the sensor is obstructed by dust or debris, cleaning the obstruction may resolve the issue.
Related DTCs: Several other DTCs may be related to the HVAC system and can provide additional clues to the cause of the B1317 code. These codes may relate to the blend door actuator, refrigerant pressure sensor, or other temperature sensors. Addressing these related codes may be necessary to fully resolve the B1317 issue.
Data Stream Parameters: When using a scan tool, monitoring relevant data stream parameters can help diagnose the root cause of the B1317 code. Key parameters to monitor include:
- In-Car Temperature Sensor Reading (displayed in degrees Celsius or Fahrenheit)
- HVAC Control Module Temperature Request
- Blend Door Position
- Refrigerant Pressure
Monitoring these parameters can help determine if the sensor is providing accurate readings, if the HVAC control module is requesting the correct temperature, and if the blend door is functioning correctly.
Impact on Vehicle Performance: The B1317 code primarily affects the comfort and efficiency of the HVAC system. Inaccurate temperature control can lead to discomfort for the vehicle's occupants. Additionally, the HVAC system may work harder than necessary to maintain the desired temperature, potentially affecting fuel economy.
Complexity of Repair: The complexity of the repair varies depending on the root cause of the problem. Replacing a faulty sensor or repairing damaged wiring is typically a relatively straightforward repair. Replacing the HVAC control module can be more complex, as it may require programming and specialized tools.
Frequently Asked Questions
What does the B1317 code mean? It means there is a fault in the in-car air temperature sensor circuit. This prevents the HVAC system from accurately reading the cabin temperature.
Can I drive with the B1317 code? Yes, but your HVAC system may not function correctly. You might experience inaccurate temperature control.
Is the B1317 code serious? It's not a safety issue, but it affects your comfort. Get it checked to restore proper HVAC function.
How do I fix the B1317 code? Troubleshoot the sensor, wiring, and HVAC module. Repair or replace faulty components.
Can a bad sensor cause other problems? Yes, it can cause the HVAC system to work inefficiently. This can lead to increased fuel consumption.
Conclusion
The B1317 code indicates a problem with the in-car air temperature sensor circuit, which can lead to inaccurate cabin temperature control and discomfort. By following the troubleshooting steps outlined in this article, you can diagnose and repair the issue, restoring proper HVAC functionality and ensuring a comfortable driving experience.