P2378 code meaning
Turbocharger/Supercharger Inlet Pressure Sensor B Circuit Intermittent/Erratic
Powertrain system Generic code P23xx codes Check engine light
What P2378 means
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.
P2378 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 2.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P2378
- Warning lamp that comes and goes
- Brief hesitation under boost
Common causes of P2378
- Most likelyLoose terminals at sensor B
- PossibleHarness damaged by heat from the turbocharger
- Less likelyMoisture in the sensor connector
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Turbocharger inlet pressure sensor bSensor wiringSensor reference voltage
What each part of P2378 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 3 | Area: ignition system or misfire. |
| 78 | The exact fault in that area. |
What to do next
- Note P2378 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P2378
What does P2378 mean?
P2378 means "Turbocharger/Supercharger Inlet Pressure Sensor B Circuit Intermittent/Erratic". P2378 records a signal from compressor inlet pressure sensor B that jumps or briefly drops out without staying beyond a limit. It is a generic code, so it means the same on every make.
Is it safe to drive with P2378?
Drive gently and only to a workshop. With P2378 the car can go into limp mode (reduced power) to protect itself.
Will P2378 fail an emissions test?
Yes, it can. P2378 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P2378 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P2378 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.