Fuel and air

P023D — MAP and Boost Pressure Sensor 'A' Correlation Fault

Severity: medium Drive with care, to a shop

What P023D means

The engine control unit constantly compares the manifold absolute pressure (MAP) sensor signal with the turbo or supercharger boost pressure sensor 'A' signal. When both sense the same air pressure, their readings should be close. If they differ by more than the allowed amount for long enough, the PCM stores P023D and turns on the check engine light.

Symptoms

  • Check engine light on
  • Reduced power and sluggish acceleration
  • Worse fuel economy
  • Rough idle or hesitation under load
  • Limp mode under heavy load

Possible causes

  1. Failed MAP sensor
  2. Failed boost pressure sensor 'A'
  3. Open, shorted or corroded wiring or connectors
  4. Vacuum or boost leaks (hoses, clamps, intercooler)
  5. Dirty or clogged sensor port
  6. PCM software or calibration issue (rare)

How to diagnose

  1. Scan all codes and freeze frame data, noting any other boost or pressure codes
  2. Inspect both sensors' connectors and wiring for damage, moisture and corrosion
  3. With the key on and engine off, compare MAP and boost sensor readings; both should show ambient pressure
  4. Compare readings at idle and under load to see which sensor is off
  5. Check 5 V reference, ground and signal wires at each sensor
  6. Pressure test the intake and boost system and inspect hoses, clamps, intercooler and vacuum lines for leaks
  7. Check the sensor and its port for oil or soot contamination
  8. Look for PCM software updates for the vehicle

Common fixes

  • Replace the faulty MAP sensor
  • Replace boost pressure sensor 'A'
  • Repair damaged wiring or connectors
  • Fix vacuum or boost leaks
  • Update or reflash the PCM software

Questions and answers

What does P023D mean?

The PCM found that the MAP sensor and boost pressure sensor 'A' report noticeably different pressures. A bad sensor, wiring problem or air leak can cause it.

Can I drive with P023D?

Briefly and carefully, yes. Expect possible power loss and limp mode. Diagnose it soon to avoid wasting fuel or stressing the turbo.

How do I tell a bad sensor from a boost leak?

With the engine off, both sensors should read ambient pressure. If they disagree, suspect a sensor or its wiring. If they match, look for leaks under load.

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.