OBD-II reference

All 9.533 generic OBD-II codes, explained in detail.

Causes, inspection steps and sources — a comprehensive DIY archive. Created and maintained with love for the detail. Good luck and have fun!

Powertrain generic / SAE

P0109

Manifold Absolute Pressure / Barometric Pressure Circuit Intermittent

The ECU detects intermittent signal dropouts on the MAP/BARO sensor circuit. Fault is not constantly present — typically caused by loose connectors, chafed wiring, or a sensor failing under thermal load.

SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number1 / 09

Possible causes

  • MAP connector loose or corroded high
  • Sensor fails when hot medium
  • Wiring chafed or pinched medium

Inspection / repair

  • Difficulty: medium
  • DIY: possible
  • Estimated cost: 40–200 €
  • Estimated time: 0.5–2 h
  • Component: map sensor
  • Component: map connector
  • Component: map wiring
  • MIL / check engine light
  • emissions-relevant
  • drive cycle required

Sources

References

How to read OBD-II codes

The first letter names the vehicle system, the second digit distinguishes generic from manufacturer-specific, the remaining digits group fault area and number.

PPowertrain: engine, transmission, emissions
BBody: chassis trim, comfort, interior
CChassis: suspension, brakes, steering
UNetwork: CAN, control modules, communication