Technical Definition:

Manifold Absolute Pressure (MAP) / Barometric Pressure (BARO) Circuit

Technical Description:

The MAP (Manifold Absolute Pressure) sensor is part of the fuel management system. It reacts to changes in engine manifold pressure. The PCM (Powertrain Control Module) monitors the MAP sensor continually to properly run the engine. Changes in engine load require changes in the amount of fuel injected, and timing of the ignition system, etc.

Possible Causes:

• MAP sensor vacuum hose disconnected or plugged
• Bad MAP sensor
• Bad TPS
• Damaged or problematic MAP sensor connector
• Damaged or problematic TPS connector
• Damaged wiring
• Short to reference voltage on signal circuit of MAP sensor
• Loss of ground to MAP sensor or TPS
• Open on signal circuit of MAP sensor
• Bad PCM

Possible Symptoms:

• Poor running engine
• Engine runs rich
• Engine won’t idle
• Engine backfires through tailpipe
• Engine misfire under load or at idle
• MIL (Malfunction Indicator Lamp) illumination
• In some extreme cases there may be no symptoms other than MIL illumination

Manifold Absolute Pressure/Barometric Pressure Circuit Malfunction

Possible Solutions:

OBD-II Trouble Code Type:

Diagnostic Step:

Tech Notes:

– Faulty Manifold Absolute Pressure sensor
– Manifold Absolute Pressure harness is open or shorted
– Manifold Absolute Pressure sensor circuit poor electrical connection
– Faulty Engine Control Module (ECM)

Specific Makes:

– Engine rough idle
– Engine hesitation