Powertrain, generic (extended)

P2378 Turbocharger/Supercharger Inlet Pressure Sensor B Circuit Intermittent/Erratic

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2378 records a signal from compressor inlet pressure sensor B that jumps or briefly drops out without staying beyond a limit. No manufacturer documents it publicly, and even for the A sensor a dedicated erratic code is rare: GM's LT4 table catches short spikes only through the counting window of its low and high checks (320 of 400 samples), and Ford's 2023 diesels fold faults of their digital sensor into P012A. An erratic monitor therefore has to look for brief limit violations or pressure changes faster than air in the intake can produce. Loose terminals, a harness touched by the hot turbocharger housing and moisture in the connector are typical. The fault tends to come and go; the ECM uses a substitute value while it is present.

Likely causes

Loose terminals at sensor B
Harness damaged by heat from the turbocharger
Moisture in the sensor connector

Symptoms

  • Warning lamp that comes and goes
  • Brief hesitation under boost

Repair estimate

DifficultyMediumDIY possible
Parts and labour€30–300
Time0.5–2.5 h

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

Parts involved

turbocharger inlet pressure sensor bsensor wiringsensor reference voltage

Related codes

P2374P2376P2377P2375P012E

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