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DTC codes / P01xx · Fuel and air metering / P01FC

P01FCTurbocharger Outlet Pressure Sensor B Circuit Low

P01FC indicates that the powertrain control module has detected an abnormally low voltage signal from the turbocharger outlet pressure sensor B circuit, which is used to monitor boost pressure after the compressor. The sensor's output is below the expected range for the current operating conditions, so the computer cannot trust the boost pressure reading.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaFuel and air metering

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms.
  • Reduced engine power or limp mode due to the computer limiting boost.
  • Poor acceleration and sluggish throttle response.
  • Decreased fuel economy because the engine may run rich or with incorrect boost.
  • In some cases, a slight hesitation or stumble during acceleration.

Common causes, most likely first

  1. Faulty turbocharger outlet pressure sensor B.
  2. Damaged or corroded wiring or connector at the sensor.
  3. Open circuit or short to ground in the sensor signal circuit.
  4. Poor electrical connection at the powertrain control module.
  5. Restricted or blocked pressure port or hose to the sensor.
  6. Excessive carbon buildup or oil contamination on the sensor element.

How to diagnose and fix it

  1. Perform a visual inspection of the sensor, connector, and wiring for damage or corrosion.
  2. Check for technical service bulletins (TSBs) related to this code for your vehicle.
  3. Use a scan tool to view live data from the turbocharger outlet pressure sensor B and compare to expected values.
  4. Measure reference voltage and ground at the sensor connector with a multimeter.
  5. Check continuity and resistance of the signal circuit between the sensor and PCM.
  6. Inspect the pressure port and hose for blockage or leaks.
  7. If electrical checks pass, replace the turbocharger outlet pressure sensor B and clear the code.

Don't overlook the pressure port and wiring

  • A clogged or restricted pressure port at the sensor is a common cause that is often missed because the sensor itself tests fine.
  • The code can be set by a poor connection at the PCM even when the sensor and wiring appear intact, so always check both ends of the circuit.
  • A low voltage signal does not always mean the sensor has failed; a short to ground in the harness can produce the same reading.
  • After replacing the sensor, verify that the live data reading changes smoothly with engine load to confirm the fix.
  • This code is specific to sensor B; if sensor A also has a code, address both circuits together to avoid repeat repairs.

Can I keep driving with P01FC?

You can usually drive the vehicle with this code, but expect reduced performance and possible limp mode; avoid heavy acceleration or towing until the fault is repaired to prevent further damage.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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