P0108 means Manifold Absolute Pressure/Barometric Pressure Circuit High Input. The MAP sensor signal is higher than expected, which the computer reads as very low vacuum or a short to voltage. It is a generic OBD-II code, so the definition is the same on any make, but the most likely cause varies by engine; confirm with a scan tool and the service information for your vehicle before buying parts.
What P0108 means
Most engine sensors receive a 5-volt reference and return a signal between roughly 0 and 5 volts. Codes ending in circuit high or circuit low usually point to an electrical fault: an open circuit, a short or an unplugged connector. Range/performance codes mean a signal is present but disagrees with what the computer expects from the other sensors, which more often points to a dirty sensor, an air leak or a mechanical problem.
P0108 symptoms
- Rough idle or black smoke
- Poor fuel economy
- Hesitation
Common causes of P0108
- Disconnected or split vacuum hose to the MAP sensor (where fitted)
- Short to voltage in the signal circuit
- Failed MAP sensor
- Mechanical problems that cause low manifold vacuum, such as incorrect valve timing
How to diagnose P0108
- Check the MAP hose and intake for leaks
- Check the wiring for shorts
- Compare MAP readings at idle with expected manifold vacuum
- Check engine vacuum with a gauge if the sensor tests good
Can you drive with P0108?
Usually drivable, but the engine may run rich. Repair it soon.
P0108 tips
A disconnected MAP vacuum hose makes the sensor read atmospheric pressure all the time, which the computer reads as wide-open throttle, so the engine runs rich at idle. Check the hose before the sensor.
Will P0108 clear itself?
If the fault stops, the computer turns off the check engine light by itself after several drive cycles without seeing it again, and the code stays in memory as history for a while. Clearing P0108 with a scan tool after a repair is fine, but if the cause is still there the code returns, sometimes within one drive. Disconnecting the battery also clears codes on most vehicles, but it erases learned fuel trims and idle settings as well.
Related codes
| Code | Meaning |
|---|---|
| P0106 | Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance |
| P0107 | Manifold Absolute Pressure/Barometric Pressure Circuit Low Input |
| P0172 | System Too Rich (Bank 1) |
Guides that help
When it is more than a sensor
Sensor codes are usually fixed with a sensor, a connector, wiring or a leak repair rather than major parts. If testing turns up internal engine trouble instead, see how to tell if an engine is blown and compare engines by code on our engines page.
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