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DTC codes / P01xx · Fuel and air metering / P012A

P012ATurbocharger/Supercharger Inlet Pressure Sensor A Circuit

P012A indicates that the powertrain control module (PCM) has detected an abnormal signal from the turbocharger or supercharger inlet pressure sensor on circuit A. This sensor measures the pressure of the air entering the turbocharger or supercharger, and the code is set when the PCM sees a voltage or rationality error that does not match expected values under current operating conditions.

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 performance or power, especially during acceleration
  • Poor fuel economy or increased fuel consumption
  • Rough idle or hesitation when the engine is cold
  • In rare cases, the engine may enter limp mode to protect the turbocharger or supercharger

Common causes, most likely first

  1. Faulty turbocharger or supercharger inlet pressure sensor
  2. Damaged or disconnected electrical connector at the sensor
  3. Wiring harness issues such as open, short, or high resistance in the sensor circuit
  4. Clogged or restricted inlet pressure sensor port due to debris or carbon buildup
  5. Leaks or blockages in the intake air system before the turbocharger or supercharger
  6. Corrosion or water intrusion in the sensor or connector
  7. PCM software issue or internal fault (less common)

How to diagnose and fix it

  1. Inspect the sensor and its connector for physical damage, corrosion, or loose pins; clean and secure as needed
  2. Check the sensor's reference voltage and ground circuits with a multimeter to verify proper power and ground
  3. Test the sensor's signal output with a scan tool to see if it correlates with actual inlet pressure (compare with barometric pressure at key-on, engine-off)
  4. Inspect the intake air ducting and sensor port for restrictions, leaks, or carbon buildup; clean or repair as necessary
  5. Replace the turbocharger or supercharger inlet pressure sensor if testing indicates it is faulty
  6. Repair or replace damaged wiring or connectors in the sensor circuit
  7. Clear the diagnostic trouble codes and perform a road test to verify the repair; reprogram the PCM if a software update is available

Before replacing the inlet pressure sensor

  • A dirty or restricted sensor port can mimic a failed sensor, so always inspect and clean the port before condemning the part.
  • The inlet pressure sensor often shares a 5-volt reference and ground with other sensors; a fault in those shared circuits can set P012A along with other codes.
  • On some vehicles, the inlet pressure sensor is integrated into the turbocharger or supercharger assembly, making replacement more involved and costly.
  • A faulty sensor may not cause any drivability symptoms, so the code can be intermittent and only appear under specific conditions.
  • After repairs, the PCM may require a relearn or adaptation reset to properly calibrate the new sensor.

Can I keep driving with P012A?

The vehicle is generally safe to drive with P012A, but avoid aggressive acceleration or heavy loads until the fault is repaired, as the engine may enter limp mode or suffer reduced performance.

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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