P0108: Manifold Absolute Pressure/Barometric Pressure Circuit High Input
Can you still drive? Yes, but the engine will run rich which wastes fuel and can foul spark plugs and damage the catalytic converter. Repair within a few days.
What Does P0108 Mean?
Code P0108 indicates that the MAP sensor voltage is higher than the maximum expected range, typically above 4.5 volts during engine operation. At idle, the MAP sensor should read around 1-2 volts due to intake vacuum. A reading near 5V at idle suggests the sensor is not detecting vacuum, the hose is disconnected, or there is a wiring short.
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An OBD-II scanner lets you read and clear diagnostic trouble codes from your vehicle's computer. Most scanners work with any car made after 1996.
Browse OBD-II Scanners on AmazonCommon Causes
- Disconnected or cracked vacuum hose to MAP sensor
- Short to voltage in MAP sensor signal wire
- Faulty MAP sensor
- Severe vacuum leak eliminating manifold vacuum
- Clogged MAP sensor vacuum port
Symptoms
- Check engine light on
- Rich running condition with black smoke
- Strong fuel odor from exhaust
- Engine surging or bucking
- Poor fuel economy
Diagnostic Steps
- 1Inspect vacuum hose from MAP sensor to intake manifold for disconnection or cracks
- 2Verify MAP sensor voltage drops below 2V at idle with engine running
- 3Check for shorts to voltage in the signal wire
- 4Clean or replace the MAP sensor vacuum port if clogged
- 5Test with a known good MAP sensor
Recommended Parts & Tools
throttle body cleaner
wiring repair kit
Estimated Repair Cost
| Type | Estimated Cost |
|---|---|
| Total Repair Cost Range | $30 - $300 |
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Frequently Asked Questions
Why does P0108 cause a rich condition?
A high MAP reading tells the ECM that intake manifold pressure is high, meaning the engine is under heavy load. The ECM responds by injecting excess fuel, resulting in a rich condition even at idle.
Can a disconnected vacuum hose cause P0108?
Yes, this is one of the most common causes. If the vacuum hose to the MAP sensor falls off, the sensor reads atmospheric pressure instead of manifold vacuum, producing a high voltage signal.
Community Fix Reports
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