HomeTrouble CodesP2378

P2378 — Turbochargersupercharger Inlet Pressure Sensor B Circuit Intermittenterratic

Manufacturer-specificPowertrain (engine & transmission)

The engine control module has detected an unstable or erratic voltage signal from the turbocharger or supercharger inlet pressure sensor (Sensor B). This indicates that the sensor's output is fluctuating outside of normal operating parameters or intermittently dropping out.

Symptoms

What causes it — most likely first

1. Faulty Inlet Pressure Sensor B

Internal component failure or worn electrical contacts within the sensor causing an unstable signal.

2. Wiring Harness Issues

Frayed wires, corroded terminals, or loose connectors causing intermittent connection to the ECM.

3. Sensor Contamination

Oil, carbon buildup, or debris obstructing the sensor element, leading to erratic pressure readings.

4. Vacuum or Pressure Leaks

Leaks in the lines leading to the sensor that cause pressure fluctuations.

5. ECM/PCM Internal Failure

A fault in the control module's processing circuit for the pressure sensor input.

How it's diagnosed

  1. Perform a visual inspection of the sensor connector and wiring for corrosion, rubbing, or damage.
  2. Check the sensor port for oil or carbon contamination and clean if necessary.
  3. Measure the reference voltage and ground at the sensor connector using a digital multimeter.
  4. Monitor the sensor output signal via a scan tool or oscilloscope to identify erratic voltage spikes or drops.
  5. Perform a wiggle test on the wiring harness while monitoring the signal to identify intermittent opens or shorts.

Code facts & related codes

SystemPowertrain (engine & transmission)
StandardizationManufacturer-specific (P1/B1/C1/U1)

Frequently asked

Can a dirty sensor cause P2378?

Yes, oil or carbon deposits on the sensing element can cause the sensor to report erratic pressure values.

Is it common to replace the PCM for this code?

No. While possible, it is very rare. Most P2378 issues are resolved by replacing the sensor or repairing the wiring harness.

Will the vehicle still run with this code?

The vehicle will typically run, but the ECM may limit boost pressure or enter a safe mode to prevent engine damage.