Powertrain, generic · Vehicle speed, idle control and auxiliary inputs

P05E2 A/C Refrigerant Pressure Sensor B Circuit Intermittent/Erratic

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

The refrigerant pressure sensor (three wires, 5 V reference, signal rising with pressure) tells the engine module the A/C pressure; it uses it to switch the radiator fan, to block the compressor at too high or too low pressure and to pre-control idle load. CARB requires such inputs to be checked for circuit faults and plausibility, but they need not light the lamp if they do not affect emissions. 'Intermittent/Erratic' means the signal jumps implausibly fast or briefly leaves its valid range without staying low or high long enough for those codes. Sensor B is a second pressure sensor; which one depends on the maker – typically the low-pressure side or a second circuit in heat pump systems. Its other codes are P2515–P2518. No manufacturer document available to us uses P05E2, so this follows the sensor A family. Expect the A/C or heat pump to switch off intermittently.

Likely causes

Loose contact or corrosion at the sensor B connector
Chafed or broken harness
Sensor B faulty
5 V reference or control module

Symptoms

  • A/C or heat pump intermittently switched off
  • Heating or cooling output fluctuates
  • Warning lamp depending on the maker

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€40–300
Time0.5–2 h

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

Parts involved

ac refrigerant pressure sensorsensor wiringengine control module

Related codes

P2515P2516P2517P2518P05E1P0534

References: law.cornell.edu, gsi.ext.gm.com, saabwisonline.com.