P2377: Turbocharger Inlet Pressure Sensor B Circuit High

What it means

The control module detects a signal above the expected range in the turbocharger or supercharger inlet pressure sensor B circuit.

At a glance

• Usually lights the check-engine light
• Affects emissions; the car can fail an emissions test

How it works

Turbocharger inlet pressure sensor B measures pressure entering the turbocharger or supercharger and sends an electrical signal to the control module. P2377 sets when that signal rises above the expected range, which can happen if the signal wire contacts a supply or the sensor ground is open.

Common causes

Most likely first.

1. Signal shorted to supply
2. Sensor ground open
3. Connector pins corroded - high contact resistance

Symptoms

• Check engine light on
• Significant power loss / limp mode
• Possible blue or black smoke from exhaust
• Whistling or hissing sound from intake

How to diagnose it

1. Check freeze-frame and live data to confirm sensor B reads high and compare it with other available intake-pressure readings.
2. Inspect sensor B's connector and harness for chafing, pinched wires, corrosion, loose terminals, or contact with a powered wire.
3. Using the wiring diagram and manufacturer's procedure, check the signal circuit for a short to supply.
4. Check sensor B's ground path and connector terminal fit for an open or high-resistance connection.
5. If the circuit checks pass, test sensor B and its pressure port to the manufacturer's procedure.

Common fixes

• Repair a signal wire shorted to supply or damaged by chafing.
• Clean or repair corroded, loose, or pushed-back connector terminals.
• Restore an open or poor ground connection for sensor B.
• Replace sensor B if it fails the manufacturer's test after wiring is verified.

Can I keep driving?

Avoid heavy acceleration if the vehicle has major power loss, smoke, or an intake hiss, and stop if it runs poorly or smoke is heavy. Arrange diagnosis soon because a falsely high sensor B reading can disrupt engine control.