Fuel and air

P01FA — Turbocharger Outlet Pressure Sensor “B” Circuit Fault

Severity: medium Drive with care, to a shop

What P01FA means

The turbocharger outlet pressure sensor tells the engine computer how much boost the turbo is producing after the compressor. The ECM uses this signal to control boost and fueling. P01FA is set when the signal from sensor B is out of range, missing or implausible, pointing to a wiring problem, a bad reading or a failed sensor.

Symptoms

  • Check Engine light on
  • Reduced power and sluggish turbo response
  • Limp mode under heavy load
  • Erratic boost readings in scan data
  • Possible rough idle
  • Unusual turbo noise (not always present)

Possible causes

  1. Failed turbo outlet pressure sensor B
  2. Damaged, shorted or corroded wiring or connector
  3. Open circuit or short to ground or power in the signal wire
  4. Low system voltage or poor ground
  5. Charge-air or vacuum leak affecting readings
  6. Turbo actuator fault or sticking variable geometry (if equipped)
  7. Internal ECM fault (rare)

How to diagnose

  1. Scan all codes and freeze-frame data, then clear the code and see if it returns
  2. Inspect the sensor connector and harness for chafing, corrosion, oil or heat damage
  3. Test battery voltage and engine ground quality
  4. Compare sensor readings with specified and actual boost in live data (key on, engine off should read near atmospheric)
  5. Use a multimeter to check the 5 V reference, ground and signal at the sensor connector
  6. Inspect intercooler pipes, hoses and vacuum lines for leaks or cracks
  7. Check turbo actuator movement over its full range
  8. If the circuit is good and readings are wrong, replace the sensor and retest

Common fixes

  • Repair or replace damaged wiring and connectors
  • Replace turbo outlet pressure sensor B
  • Fix charge-air or vacuum leaks and bad hoses
  • Repair or replace the turbo actuator if faulty
  • ECM repair, reprogramming or replacement (rare)

Questions and answers

Can I drive with P01FA?

You can for a short time if you go easy on the engine. The car may lose power in limp mode, and poor boost control is not good for the engine.

What most often causes P01FA?

Usually damaged wiring or a connector at the sensor, or the pressure sensor itself. Check the circuit and look for air leaks before replacing parts.

Do I need a new turbo for P01FA?

Usually not. The code points to the sensor circuit, so test the sensor and wiring first and look at the turbo only if it shows signs of failure.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.