Fuel and air

P023E — MAP and Boost Sensor B Correlation Fault

Severity: medium Drive with care, to a shop

What P023E means

The engine control unit compares the manifold absolute pressure (MAP) sensor with boost pressure sensor B in the turbo or supercharger air path. Under the same conditions the two readings should match or differ by an expected amount. When they disagree beyond tolerance, the ECU can't tell which one to trust and sets P023E.

Symptoms

  • Check Engine light on
  • Weak acceleration and reduced power
  • Loss of boost or limp mode
  • Hesitation or surging under acceleration
  • Poor fuel economy
  • Unusual noises from the intake under boost

Possible causes

  1. Failed MAP sensor
  2. Failed boost pressure sensor B
  3. Wiring or connector damage, corrosion, or poor contact
  4. Boost or vacuum leaks in hoses, clamps, pipes, or the intercooler
  5. Clogged or dirty sensor port
  6. Rarely, ECU software fault

How to diagnose

  1. Scan all codes and freeze-frame data and look for other boost or intake codes
  2. Inspect sensor connectors and wiring for corrosion, chafing, and damage
  3. With key on and engine off, compare MAP and sensor B readings; both should be near ambient pressure
  4. Test 5 V reference, ground, and signal at each sensor with a multimeter or scope
  5. Inspect hoses, clamps, and the intercooler for cracks, oil, or leaks; pressure test the system if needed
  6. Compare live data from both sensors under load and decide which one is wrong
  7. Check sensor ports and vacuum lines for blockage
  8. Check for ECU software updates for your vehicle

Common fixes

  • Replace the faulty MAP sensor
  • Replace boost pressure sensor B
  • Repair wiring and connectors
  • Fix boost leaks: replace hoses, clamps, or the intercooler
  • Update or reflash the ECU software

Questions and answers

What does P023E mean?

The ECU found that the MAP sensor and boost pressure sensor B report noticeably different pressures. The cause may be a sensor, wiring, or an air leak in the boost path.

Can I drive with P023E?

Briefly and carefully, for example to a shop. Power is usually limited, and prolonged driving with bad boost data can harm the engine.

What should I check first?

Start with the sensor connectors and wiring, then look for leaks in the hoses and intercooler. If those are fine, compare both sensors' live data and replace the one giving wrong values.

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.