P2378Turbocharger/Supercharger Inlet Pressure Sensor B Circuit Intermittent/Erratic
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- 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.
- What you may notice
- Warning lamp that comes and goes
- Brief hesitation under boost
- Likely causes
- LikelyLoose terminals at sensor B
- PossibleHarness damaged by heat from the turbocharger
- RareMoisture in the sensor connector
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €30 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.