Powertrain, generic (extended)

P2B7E EVAP System Pressure Sensor/Switch C Circuit Intermittent

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P2B7E covers a signal from EVAP pressure sensor C that drops out or jumps for brief moments instead of failing for good. No manufacturer documents P2B7E publicly; Audi and VW use only P2B7A and P2B7B, VW also P2B7C and P2B7D, for this sensor. How such a check can work is shown by Mitsubishi's 2023 Outlander PHEV for its tank pressure sensor (P24D9): during the parked leak test it counts how often the signal crosses its own filtered value and sets the code after more than 20 crossings. Loose terminals, a chafed harness near the tank, moisture in the connector or electrical interference – the cause Mercedes-AMG found behind P2B7B – are typical. CARB 13 CCR 1968.2 (e)(15) asks for circuit checks on EVAP inputs. Moving the harness gently while the reading is displayed helps locate the spot.

Likely causes

Loose or corroded terminal at the sensor connector
Harness chafing near the tank or along the underbody
Electrical interference on the signal line
Pressure sensor C with an intermittent internal fault

Symptoms

  • Check engine light comes and goes
  • Pressure reading jumps in live data
  • Fault often appears only on rough roads or in wet weather

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€40–400
Time0.5–3 h

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

Parts involved

evap pressure sensor cwiring harnessecm

Related codes

P2B7AP2B7BP24D9P0454

References: law.cornell.edu, mitsubishitechinfo.com, static.nhtsa.gov.