P023D: Manifold Absolute Pressure - Turbocharger/Supercharger Boost Sensor A Correlation

What it means

The manifold absolute pressure reading and boost pressure sensor A reading do not agree within the calibrated limits.

At a glance

• Usually lights the check-engine light
• Affects emissions; the car can fail an emissions test

How it works

The MAP sensor measures pressure in the intake manifold, while boost sensor A measures pressure at a separate point in the turbocharger or supercharger system. The module compares these readings under monitored conditions and sets P023D when they disagree beyond the calibrated limits.

Common causes

Most likely first.

1. MAP sensor reading inaccurate
2. Boost sensor A reading inaccurate
3. Damaged wiring or connector
4. Intake or boost pressure issue

Symptoms

• Check engine light on
• Significant power loss / limp mode
• Possible blue or black smoke from exhaust
• Whistling or hissing sound from intake

How to diagnose it

1. Review freeze-frame data and graph MAP and boost sensor A readings to identify when their disagreement begins.
2. With the engine off, compare the sensors' readings under the same pressure conditions using a scan tool and the manufacturer's procedure.
3. Inspect the MAP sensor, boost sensor A, their connectors, and wiring for damage, loose fit, contamination, or poor connections.
4. Check intake and charge-air plumbing for loose joints, splits, leaks, or restrictions that could make the pressures differ.
5. Test each sensor and its wiring against the manufacturer's specifications before replacing either sensor.

Common fixes

• Reconnect or repair a loose or damaged MAP or boost sensor A connector.
• Repair a leaking or damaged intake or charge-air hose.
• Repair damaged wiring or poor terminal connections.
• Replace the MAP sensor or boost sensor A only if testing identifies it as inaccurate.

Can I keep driving?

With significant power loss or limp mode, avoid overtaking and heavy acceleration, and limit driving to what is needed to reach a safe place for diagnosis. Stop if smoke becomes heavy or the engine runs roughly.