How serious is this DTC?
In my opinion, the severity of any HVAC-related code will be quite low. In this case, pressurized refrigerant is involved, so it might be more of an urgent issue. Who knows, a refrigerant leak could be causing this code, and a refrigerant leak is certainly a hazard, so make sure you have some basic knowledge of refrigerant safety before attempting any kind of repair on the air conditioning system.
What are some of the symptoms of the code?
Symptoms of a P2516 diagnostic code may include:
- Inaccurate temperatures from the fan air
- Limited HVAC operation
- Erratic/fluctuating fan air temperature
- Air conditioning compressor not engaging when needed
- HVAC system operating abnormally
What are some common causes of the code?
Causes
of this P2516 transmission code may include:
- Faulty or damaged A/C refrigerant pressure sensor
- Leak in the air conditioning refrigerant pressure sensor
- Low or incorrect refrigerant pressures/level
- Damaged wire(s) (open, short to +, short to -, etc.)
- Damaged connector
- ECC (Electronic Climate Control) or BCM (Body Control Module) issue
- Poor connections
What are the diagnostic and troubleshooting steps for P2516?
Before starting the troubleshooting process for any malfunction, you should look up the technical service bulletins (TSBs) for the specific vehicle by year, model, and transmission. This step can save you time and money during diagnosis and repair!
Basic Step #1
Depending on the tools/knowledge you have access to, you can easily check the operation of the A/C refrigerant pressure sensors. The two simple ways to do this are: 1. Depending on the capabilities and limitations of your OBD reader/scan tool, you may be able to monitor refrigerant pressures and other desired values while the system is running to check sensor functionality. 2. If you have a set of A/C manifold gauges, you can monitor pressures mechanically and compare the pressures with the specific desired values from your manufacturer.
TIP: If you have no experience with refrigerant, I would not recommend diving into pressure testing, so make sure you’re not in over your head here; refrigerant is an environmental hazard, so it’s not something to play around with.
Basic Step #2
Test the A/C refrigerant pressure sensor. As I mentioned earlier, most of the time, this sensor is a 3-wire pressure transducer. That said, testing it will involve testing between the pins and recording your results. The desired values for this test vary significantly between manufacturers, temperatures, sensor type, etc., so make sure your information is accurate.
NOTE: Make sure to use the appropriate test pins with your multimeter when testing pins/connectors. A damaged pin or connector could cause future intermittent electrical gremlins that are hard to find.
Basic Step #3
Check the wiring. Sometimes these sensors will be mounted on an air conditioning 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 because the line wasn’t properly secured. Make sure the sensor is in good physical condition and the line is properly attached.
