P0108
UniversalManifold Absolute Pressure/Barometric Pressure Circuit High Input
Medium SeverityThis code indicates that the engine's computer (PCM) has detected a voltage signal from the Manifold Absolute Pressure (MAP) sensor or Barometric Pressure (BARO) sensor that is higher than expected. This can lead to incorrect fuel mixture, impacting engine performance and fuel efficiency.
⚠️ Before You Begin (Safety First)
Always ensure the engine is off and cool before performing any work. Disconnect the negative battery terminal to prevent accidental shorts or electrical shocks. Wear appropriate personal protective equipment, such as safety glasses and gloves.
Common Symptoms
- Check Engine Light illuminated
- Poor engine performance
- Reduced fuel economy
- Rough idle
- Engine hesitation or stalling
- Difficulty starting
Common Causes
- Faulty Manifold Absolute Pressure (MAP) sensor
- Faulty Barometric Pressure (BARO) sensor (if applicable)
- Short to voltage in the MAP/BARO sensor circuit wiring
- Corroded or loose electrical connectors at the sensor or PCM
- Damaged PCM (Powertrain Control Module) - rare
Frequently reported on: Honda Civic 2001-2005, Ford F-150 2004-2008, Toyota Camry 1997-2001, Chevrolet Silverado 1999-2006
Diagnostic Steps
- Visually inspect the MAP sensor and its electrical connector for any obvious damage, corrosion, or loose connections. Ensure the sensor is securely mounted.
- Check the wiring harness leading to the MAP sensor for any signs of cuts, chafing, or heat damage. Repair any damaged wires.
- Clear the P0108 code with an OBD-II scanner and test drive the vehicle to see if the code returns.
- If the code persists, and after verifying the wiring is intact, carefully remove the MAP sensor and inspect its port for any carbon buildup or obstructions. Clean if necessary.
- If all other steps fail and you suspect the sensor, replace the MAP sensor with a new, quality replacement part specific to your vehicle.
- After replacement, clear the code and perform another test drive.
👨🔧 When to Call a Professional
If basic inspection and sensor replacement do not resolve the P0108 code, or if you encounter complex wiring issues or observe other engine performance problems like misfires or stalling, it is best to consult a professional mechanic for advanced diagnostics.
Commonly Asked Questions
What does a MAP sensor do?
The Manifold Absolute Pressure (MAP) sensor measures the pressure inside your engine's intake manifold. This data, along with other sensor inputs, helps the engine computer determine how much fuel to inject for optimal combustion and emissions control.
Can I drive with a P0108 code?
While you might be able to drive with a P0108 code, it is not recommended for extended periods. The engine's performance, fuel economy, and emissions will likely be compromised, and prolonged driving could potentially lead to further engine damage or component wear.
How can I test a MAP sensor at home?
Testing a MAP sensor typically involves using a multimeter to measure voltage output across different vacuum levels (often simulated with a hand vacuum pump) and comparing these readings to your vehicle's specific service manual specifications. You can also check for proper reference voltage and ground at the sensor connector.
Is replacing a MAP sensor a difficult DIY repair?
For most vehicles, replacing a MAP sensor is a relatively straightforward process, often involving removing one or two mounting bolts and disconnecting an electrical connector. It is generally considered an easy to medium difficulty DIY repair that most enthusiasts can perform.
Will cleaning the MAP sensor fix the P0108 code?
Sometimes, deposits can build up on the MAP sensor tip, affecting its accuracy. You can try carefully cleaning it with an approved electrical contact cleaner or throttle body cleaner. However, if the sensor is internally faulty or the circuit has an electrical issue, cleaning alone will not resolve the P0108 code.