Technical Description of OBD-II Trouble Code
The circuit for the A/C refrigerant pressure sensor B is experiencing low voltage.
What does that mean?
This is a generic diagnostic trouble code (DTC) that is commonly found in OBD-II vehicles, including Chevrolet / Chevy, Ford, Volvo, Dodge, Hyundai, Vauxhall, Honda, Nissan, Renault, Alfa Romeo, and others.
The A/C refrigerant pressure sensor plays a role in helping the HVAC (Heating, Ventilation, and Air Conditioning) system maintain the desired temperature inside the vehicle. It does this by regulating the air conditioning system’s pressure according to your preferences.
The sensor is monitored by either the BCM (Body Control Module) or the ECC (Electronic Climate Control) Module. These modules determine the system pressures and can engage or disengage the compressor accordingly.
The A/C refrigerant pressure sensor is a pressure transducer that converts the pressure of the refrigerant system into an analog electrical signal. This allows the vehicle’s modules to monitor the pressure. Typically, the sensor uses three wires: a 5-volt reference wire, a signal wire, and a ground wire. The modules compare the values of the signal wire to the 5-volt reference and can calculate the system pressures based on this information.
When the ECM (Engine Control Module) detects a fault within the A/C refrigerant pressure sensor or its circuits, it illuminates the MIL (Malfunction Indicator Lamp) and sets the P2517 code. Associated codes may include P2515, P2516, P2517, and P2518. It is important to note that working with pressurized refrigerant can be hazardous, so proper precautions should be taken before diagnosing or repairing the A/C system.
The P2517 code is set when one of the modules detects a low electrical value in the A/C refrigerant pressure sensor B or its circuit. An example of an A/C refrigerant pressure sensor is shown below:
What is the severity of this DTC?
In my opinion, the severity of any HVAC-related code is generally low. However, in this case, since pressurized refrigerant is involved, it may be more urgent to address the issue. There is a possibility that a refrigerant leak is causing the code, and leaking refrigerant can be hazardous. Therefore, it is important to have basic knowledge of refrigerant safety before attempting any repairs on the A/C system.
What are some of the symptoms of the code?
Symptoms of a P2517 diagnostic code may include:
What are some of the common causes of the code?
Causes for this P2517 transmission code may include:
What are some P2517 diagnostic and troubleshooting steps?
Prior to beginning the troubleshooting process for any malfunction, it is recommended to research the Technical Service Bulletins (TSB’s) for the specific vehicle by year, model, and transmission. This step can save time and money during diagnosis and repair!
Basic Step #1
Depending on the tools and knowledge available, you can easily verify the operation of the A/C refrigerant pressure sensor. There are two easy ways to do this: 1. Depending on the capabilities of your OBD reader/scan tool, you may be able to monitor refrigerant pressures and other desired values while the system is operating to verify the functionality of the sensor. 2. If you have an A/C manifold gauge set, you can mechanically monitor the pressures and compare them with the manufacturer’s specified values.
TIP: If you have no experience with refrigerant, it is not recommended to perform pressure testing. Refrigerant is hazardous to the environment, so caution should be exercised.
Basic Step #2
Test the A/C refrigerant pressure sensor. As mentioned earlier, this sensor is typically a 3-wire pressure transducer. Testing it will involve testing between the pins and recording the findings. The desired values for this test can vary significantly between manufacturers, temperatures, and types of sensors, so it is important to ensure accurate information.
NOTE: When testing pins/connectors, make sure to use the appropriate test pins along with a multimeter. A damaged pin or connector could cause future intermittent electrical issues that are difficult to diagnose.
Basic Step #3
Check the wiring. Sometimes these sensors are mounted on an A/C pressure line or near a line connection, so the harness will be routed accordingly. I have personally seen these sensors damaged by moving parts under the hood due to inadequate securing of the line. Make sure the sensor is physically intact and the line is properly fastened.
