P0108Manifold Absolute Pressure/Barometric Pressure Sensor Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- 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. P0108 means the signal voltage is above its upper limit – typically an open ground (low reference), a signal wire shorted to 5 V or battery voltage, or a failed sensor. Like P0107 it describes the voltage, not real overpressure; genuinely excessive boost is P0234. Documented limits: GM petrol above 86 % of 5 V, GM diesel above 97 %, GM/Saab 2.0T above 4.80 V for 4 s, Ford above 4.88–4.96 V for 5 s. The engine substitutes a modelled value, which often makes the mixture too rich; turbo engines limit boost.
- What you may notice
- Check engine light on
- Rich mixture, sooting, higher consumption
- Rough idle, loss of power or limp mode on turbo engines
- Likely causes
- LikelyGround (low reference) wire open or connector corroded
- PossibleSignal wire shorted to 5 V or battery voltage
- PossibleMAP sensor failed internally
- RareEngine control module faulty
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · Often possible to do yourself.Typical cost: €20 – €200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.