P0109

Manifold Absolute Pressure/Barometric Pressure Sensor Circuit Intermittent

Q: Is it safe to drive with P0109?

Short trips are usually fine, but because the MAP signal helps set fueling, an intermittent dropout can cause stalling or hard hesitation. Fix it promptly if the engine cuts out or surges.

Q: Can I just clear P0109?

It will return whenever the signal glitches again. Since this is an intermittent code, concentrate on the connector and wiring before replacing the sensor.

Fuel & air metering Generic OBD-II High

What it means

P0109 means the computer detected an intermittent, dropping-out signal from the MAP (manifold absolute pressure) sensor, which measures intake pressure to help set fueling. Because the reading comes and goes, the fault is most often a loose connector or chafed wire, and it can cause hesitation or stalling when the signal glitches.

High

Can I keep driving? You can usually drive, but an intermittent MAP signal can cause sudden hesitation or stalling, so treat it as urgent if the engine surges or cuts out.

Real-world scan data

Seen in

scans in the past year

Found in

<0.1%

of scans

<0.1%

of scans that found faults

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

Common symptoms

What you'll notice

Check-engine light on
Hesitation, surging, or occasional stalling
Poor fuel economy
Lack of power on acceleration

Common causes

Most likely first

Loose or corroded connector at the MAP sensor (most common for an intermittent fault)Likely
Chafed or intermittently broken wiring in the sensor circuitCommon
Failing MAP/barometric pressure sensor with a dropping-out signalCommon
Vacuum leak or damaged vacuum line to the sensorLess often
Rarely, an ECM/PCM faultLess often

How to diagnose & fix

Work through it in order

Read freeze-frame data to see the conditions when the signal drops out.
Inspect the MAP sensor connector and pins for corrosion, spread terminals, or looseness.
Wiggle-test the harness and connector with the engine running to reproduce the fault.
Check the sensor's vacuum source (if applicable) and the signal, ground, and reference wires.
Replace the MAP sensor if the wiring and connector are good. Clear and re-test.

FAQ

Quick answers

Is it safe to drive with P0109?+

Short trips are usually fine, but because the MAP signal helps set fueling, an intermittent dropout can cause stalling or hard hesitation. Fix it promptly if the engine cuts out or surges.

Can I just clear P0109?+

It will return whenever the signal glitches again. Since this is an intermittent code, concentrate on the connector and wiring before replacing the sensor.

Read & clear P0109 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX