Fuel and air

P012D — Turbocharger/Supercharger Inlet Pressure Sensor Circuit High

Severity: medium Drive with care, to a shop

What P012D means

The engine control unit detected a voltage from the turbocharger (supercharger) inlet pressure sensor that is above the expected range. This sensor measures air pressure ahead of the compressor, and the ECU uses it to calculate boost and control the turbo. A high signal points to a faulty sensor, a wiring open or short in its circuit, or a wrong pressure reading.

Symptoms

  • Check Engine light on
  • Reduced power or limp mode
  • Sluggish acceleration or hesitation
  • Rough running or misfires
  • Possible stalling at idle
  • Higher fuel consumption
  • Unusual turbo noise

Possible causes

  1. Failed turbo/supercharger inlet pressure sensor
  2. Damaged, corroded or chafed wiring and connector at the sensor
  3. Open ground or signal wire shorted to the 5 V reference
  4. Clogged air filter or damaged intake tract skewing the reading
  5. Turbo actuator fault or sticking variable geometry mechanism
  6. Charge-air or vacuum leak
  7. ECU fault (rare)

How to diagnose

  1. Read all codes and freeze-frame data and look for other boost-related codes
  2. Inspect the sensor connector and harness for corrosion, oil, chafing or loose pins
  3. Check live data with the engine off: the sensor should read close to ambient pressure
  4. Test the 5 V supply, ground and signal wire with a multimeter for opens and shorts to power
  5. Inspect the air filter and intake path ahead of the turbo
  6. Compare specified and actual boost with live data under load
  7. Check hoses, clamps and vacuum lines for leaks
  8. Check actuator movement over its full range

Common fixes

  • Replace the turbo inlet pressure sensor
  • Repair or replace the damaged wiring and connector
  • Replace the air filter and restore intake sealing
  • Replace a faulty turbo actuator or free a sticking geometry mechanism
  • Reflash or replace the ECU only after everything else is ruled out

Questions and answers

What does P012D mean?

The ECU is getting a too-high signal from the turbo inlet pressure sensor circuit. The cause is most often the sensor itself or its wiring.

Can I drive with P012D?

Briefly, yes, but the engine will likely go into limp mode with reduced power. Diagnose it soon to avoid stressing the turbo.

How do I clear P012D?

Clearing the code with a scan tool only helps temporarily. Find and fix the cause first, or the code will return.

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.