Fuel and air

P012A — Turbo/Supercharger Inlet Pressure Sensor 'A' Circuit Fault

Severity: medium Drive with care, to a shop

What P012A means

The turbo inlet pressure sensor tells the engine control unit how much air pressure is in the intake path. The PCM uses this signal to calculate boost, fuel delivery and turbo actuator control. P012A sets when the signal from sensor 'A' is out of range, missing, erratic or doesn't match the expected pressure.

Symptoms

  • Check Engine light on
  • Reduced power or no boost
  • Limp mode
  • Worse fuel economy
  • Rough idle or hesitation under throttle
  • Unusual turbo noise

Possible causes

  1. Failed turbo/supercharger inlet pressure sensor
  2. Damaged or corroded sensor wiring or connector
  3. Poor sensor power or ground
  4. Boost or vacuum leak in hoses or intercooler
  5. Clogged air filter or intake restriction
  6. Faulty turbo actuator or sticking variable geometry mechanism
  7. PCM fault (rare)

How to diagnose

  1. Scan all codes and freeze frame data, clear the code and see if it returns
  2. Inspect the sensor connector and harness for corrosion, chafing, oil contamination and broken wires
  3. Check sensor supply voltage, reference voltage and ground at the connector
  4. Compare the sensor reading with key on, engine off against ambient barometric pressure
  5. Compare specified and actual boost in live data during acceleration
  6. Inspect hoses, clamps, intercooler and vacuum lines, and smoke or pressure test for leaks
  7. Check turbo actuator movement over its full range
  8. Inspect the air filter and intake path for restriction

Common fixes

  • Replace the turbo inlet pressure sensor
  • Repair or replace damaged wiring and connectors and clean the contacts
  • Fix boost leaks and replace damaged hoses or clamps
  • Replace the air filter
  • Repair or replace the turbo actuator or variable geometry mechanism
  • Replace or reprogram the PCM only after confirming it is faulty

Questions and answers

What does P012A mean?

It is a circuit fault in turbo/supercharger inlet pressure sensor 'A'. The PCM sees an incorrect or unstable boost pressure signal and may limit engine power.

Can I drive with P012A?

Briefly and carefully to a shop, expecting reduced power. If you notice turbo noise, smoke or a big loss of power, stop driving to protect the turbo.

Do I always need to replace the sensor for P012A?

No. Check the wiring, connector, power, ground and intake sealing first. Replace the sensor only if the circuit is good and the readings are wrong.

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.