P0109Powertrain
Powertrain · SAE
MAP/BARO Sensor Circuit Intermittent
Meaning
The manifold absolute pressure (MAP) or barometric pressure sensor signal is intermittent. The fault is not continuously present, causing unpredictable mixture and timing variations when active.
Common causes
- Loose connector or corroded pin (most common)
- Cracked vacuum reference hose vibrating in and out of contact
- Internally marginal sensor
Symptoms
- Intermittent MIL
- Erratic idle when fault is active
- Fluctuating fuel trims
- Hesitation
Severity
Moderate severity: intermittent MAP signal interruptions cause unexpected mixture and timing variations.
What to do
- Wiggle harness and connector while monitoring MAP signal live
- Inspect vacuum hose for micro-cracks
- Clean and reseat the connector
- Replace sensor if no other cause is found