Powertrain, generic · Fuel and air metering

P0109 Manifold Absolute Pressure/Barometric Pressure Sensor Circuit Intermittent

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

The manifold absolute pressure (MAP) sensor measures the pressure behind the throttle; on vehicles without a separate barometric sensor it also supplies the ambient pressure, read at key-on or wide-open throttle – hence 'MAP/BARO'. It is a three-wire sensor with 5 V reference, ground and signal. P0109 counts brief range violations of the signal that are too short for P0107/P0108 – the typical signature of a loose contact. Ford counts excursions below 0.024 V or above 4.96 V and sets the code after 25 events per drive cycle (2020–2023; ten in 2012). Ford treated it as a code without warning light in 2012 but lights the MIL in 2020–2023, so the warning-light behaviour depends on the manufacturer. GM does not use P0109 in the tables checked; there short dropouts accumulate in P0107/P0108.

Likely causes

Loose contact at the MAP connector, terminals spread or corroded
Chafed or broken wire that makes contact with engine movement
Sensor with internal dropouts
Ground problem or control module

Symptoms

  • Check engine light on (depending on manufacturer)
  • Occasional hesitation or stumble
  • Fault comes and goes

Repair estimate

DifficultyEasyDIY possible
Parts and labour€20–200
Time0.3–1.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

manifold absolute pressure sensorsensor wiringsensor reference voltage

Related codes

P0105P0106P0107P0108

References: law.cornell.edu, fordservicecontent.com, newtonnet.co.uk.