Faulty turbocharger outlet pressure sensor A or B, such as internal drift or contamination.; Damaged or corroded wiring or connectors in the sensor circuit, including open or short circuits.; Leaking or restricted pressure hose or passage supplying the sensor, causing a delayed or inaccurate signal.; Excessive carbon buildup or oil sludge blocking the sensor port or intake tract.; ECM software issue or internal fault in the pressure signal processing circuit.; Aftermarket performance modifications or incorrect sensor replacement that does not match OEM specifications.; Mechanical issue with the turbocharger itself, such as a sticking wastegate or variable geometry mechanism, causing actual pressure to deviate from commanded.

DTC codes / P01xx · Fuel and air metering / P01FF

P01FFTurbocharger Outlet Pressure Sensor A/B Correlation

Q: What does code P01FF mean?

Turbocharger Outlet Pressure Sensor A/B Correlation. P01FF is a generic powertrain code indicating that the engine control module (ECM) has detected a correlation fault between two turbocharger outlet pressure sensor signals, typically designated Sensor A and Sensor B. The ECM compares the readings from these sensors under specific operating conditions and sets the code when the difference exceeds a calibrated threshold for a set time, indicating that one sensor is reporting a pressure that does not agree with the other or with expected model values.

P01FF is a generic powertrain code indicating that the engine control module (ECM) has detected a correlation fault between two turbocharger outlet pressure sensor signals, typically designated Sensor A and Sensor B. The ECM compares the readings from these sensors under specific operating conditions and sets the code when the difference exceeds a calibrated threshold for a set time, indicating that one sensor is reporting a pressure that does not agree with the other or with expected model values.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering

Symptoms you may notice

Illumination of the malfunction indicator lamp (MIL) on the dashboard.
Often no symptoms besides the warning light, especially if the fault is intermittent or only occurs under narrow conditions.
Reduced engine power or limp mode if the ECM substitutes a default value and limits turbocharger boost.
Poor acceleration or sluggish throttle response due to incorrect boost pressure estimation.
Rough running or hesitation if the faulty signal affects fuel delivery calculations.
Possible increased fuel consumption as the ECM adjusts fueling based on inaccurate pressure data.

Common causes, most likely first

Faulty turbocharger outlet pressure sensor A or B, such as internal drift or contamination.
Damaged or corroded wiring or connectors in the sensor circuit, including open or short circuits.
Leaking or restricted pressure hose or passage supplying the sensor, causing a delayed or inaccurate signal.
Excessive carbon buildup or oil sludge blocking the sensor port or intake tract.
ECM software issue or internal fault in the pressure signal processing circuit.
Aftermarket performance modifications or incorrect sensor replacement that does not match OEM specifications.
Mechanical issue with the turbocharger itself, such as a sticking wastegate or variable geometry mechanism, causing actual pressure to deviate from commanded.

How to diagnose and fix it

Perform a visual inspection of both turbocharger outlet pressure sensors, their connectors, and the pressure hoses for damage, leaks, or blockage.
Use a scan tool to read live data from both sensors and compare their readings with key-on-engine-off and during a test drive to identify which sensor is inaccurate.
Check the sensor reference voltage and ground circuits with a multimeter to rule out wiring faults.
Inspect the sensor ports and intake passages for carbon buildup or oil residue and clean if necessary.
If one sensor is suspect, swap it with a known-good unit of the same part number and recheck the correlation.
Verify that the ECM has the latest calibration and reprogram if a software update is available.
If the fault persists after electrical and mechanical checks, replace the faulty sensor and clear the code to confirm the repair.

What the correlation code really means

A correlation code does not automatically mean a sensor has failed; it often indicates a mechanical issue such as a boost leak or a sticking turbocharger component that causes the two sensors to disagree.
On engines with a single turbocharger outlet pressure sensor, P01FF may still set if the ECM uses a modeled pressure value as the second reference, so a faulty sensor or a mechanical boost deviation can trigger it.
Technicians commonly overlook a restricted or leaking pressure hose to the sensor, which can cause a delayed signal that only fails correlation under transient conditions.
Aftermarket sensors or incorrect part numbers can produce a signal that is close but not identical to the OEM sensor, leading to a persistent correlation code even after replacement.
The code may be stored alongside boost control or mass air flow codes, so always diagnose those first as they can cause the pressure correlation to fall out of range.

Can I keep driving with P01FF?

The vehicle can usually be driven with caution, but avoid heavy acceleration or sustained high-load conditions because inaccurate boost pressure data may cause poor performance or increased emissions. If the engine enters limp mode or drivability worsens, have the fault diagnosed promptly to prevent potential turbocharger damage.

Tools that help

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