P2516: A/C Refrigerant Pressure Sensor B Circuit Range/Performance

P2516 flags a pressure sensor B whose reading is electrically valid but does not behave like real refrigerant pressure. In GM's hybrid OBD tables sensor B is the low-side sensor, evaluated by the hybrid processor that also runs the electric compressor. The 2019 edition looks for a stuck sensor: once the car has soaked and the compressor starts, the low-side value must shift by at least 4.0 kPa within 180 s of compressor running; if it barely moves, the test fails, type B with two trips. The 2011 edition used a sample counter of 32 fails in 40 checks at 250 ms intervals. GM also blocks its charge-loss check P0534 while P2516 is active. Out-of-range voltages are P2517 and P2518 instead. Typical result: compressor control falls back to defaults, cooling is weaker.

Low severity. Can I keep driving?Yes, you can keep driving. The air conditioning may not work.

Symptoms

A/C cools poorly
Check engine light after two drives (GM type B)
Refrigerant charge diagnosis not completed

Most likely causes

Pressure sensor stuck at one value
Compressor runs but hardly changes pressure (very low charge, blockage)
High resistance in signal or ground wire

What to check, in order

Start with the simplest. You can tick off each step.

Check the sensor pressure in live data
Compare the reading with other engine data while varying the engine speed.
Check the relay and connector
Have the refrigerant charge and any leaks checked at a repair shop authorized to handle refrigerant

Good to know

Repair difficulty: medium
It affects emissions.

What each character of P2516 means

P: Powertrain: engine and transmission
2: Generic code: same on every make
5: Speed and idle
16: Specific fault in that system

Frequently asked questions

Can I keep driving with code P2516?

Yes, you can keep driving. The air conditioning may not work.

What causes code P2516?

The most common causes are: pressure sensor stuck at one value; compressor runs but hardly changes pressure (very low charge, blockage); high resistance in signal or ground wire.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.