Powertrain, generic (extended)

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

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

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.

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

Symptoms

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

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–450
Time0.5–2.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

ac pressure sensor brefrigerant charge

Related codes

P2515P2517P2518P0534

References: gsi.ext.gm.com, gsi.ext.gm.com.