Manifold Absolute Pressure/Barometric Pressure Circuit High Input
Your engine's air pressure sensor is telling the computer the intake manifold pressure is too high, like a barometer stuck on an unrealistic reading. This makes the engine run too rich because it thinks there's more air than actually exists.
The MAP sensor measures intake manifold vacuum/pressure as a voltage signal. The ECM expects this signal to stay within normal operating range. When voltage exceeds the upper threshold, the ECM interprets it as abnormally high pressure and sets P0108.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| MAP Sensor Voltage | 0.5–4.5V (varies by engine load) | >4.8V or electrical signal above expected maximum |
| Manifold Pressure | 10–100 kPa at idle/cruise | Signal reads higher than physically possible for engine state |
Code P0108 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P0108 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.