P0108
Manifold Absolute Pressure/Barometric Pressure Circuit High Input
Powertrain Fuel and Air Metering Air Intake Pressure Sensing 🟡 Moderate — Fix within a week
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What This Actually Means
In plain language — no jargon

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.

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Symptoms You May Notice
3 known symptoms for this code
Check Engine Light illuminated
Engine running rich; black smoke from exhaust or fuel smell
Poor fuel economy and sluggish acceleration
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Embedded Systems Insight
What the ECU/ECM is actually computing

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.

Voltage & Parameter Thresholds

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
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
MAP sensor connector
Inspect and clean the connector for corrosion or loose pins that cause false high voltage.
2
MAP sensor wiring harness
Check for damaged insulation, pinched wires, or shorts to power that pull the signal voltage too high.
3
MAP sensor
Replace the sensor if voltage remains high after cleaning connections; internal failure is common.