P0108 Code: MAP/Barometric Pressure Circuit High Input
Note: We do not currently have verified model-specific diagnostic data for the Mazda Mx-5. The symptoms and fixes listed below are the standard generic OBD2 guidelines for the P0108 code. Always consult a factory service manual before replacing parts.
What does this mean?
Code P0108 signifies that the Powertrain Control Module (PCM) has detected an excessively high voltage signal from the Manifold Absolute Pressure (MAP) sensor. This high voltage typically corresponds to a low vacuum condition (or high pressure) within the intake manifold, which the PCM interprets as a heavy engine load or wide-open throttle. However, if this signal is present under conditions where a high vacuum (low pressure) is expected, such as at idle, it indicates a discrepancy. This can lead to incorrect fuel delivery, poor engine performance, reduced fuel economy, and potentially other drivability issues. The MAP sensor measures the absolute pressure inside the intake manifold and sends this data to the PCM, which uses it to calculate engine load and adjust fuel injection and ignition timing. A consistently high input suggests either a faulty sensor, an electrical issue in the circuit, or a genuine low vacuum condition.
How serious is this code?
Driving with a P0108 code can lead to significant drivability issues, including rough idle, hesitation, poor acceleration, reduced fuel economy, and potentially a rich running condition that could damage the catalytic converter over time. The PCM may enter a 'limp home' mode or use default values, which can severely impact engine performance and emissions. While the vehicle may still be operational, it is advisable to address the issue promptly to prevent further damage to critical components and ensure safe, reliable operation.
Most Common Causes for Mazda Mx-5
- Faulty MAP (Manifold Absolute Pressure) sensor
- Damaged, chafed, or broken wiring harness
- Corroded or loose electrical connector
- Vacuum leak in intake system
Symptoms to Watch For
- Check Engine Light is illuminated
- Rough or unstable idle
- Decreased fuel economy
- Poor acceleration or sluggish response
Before replacing parts, check these first
- Check for blown fuses related to the circuit.
- Inspect the wiring harness and electrical connectors for visible damage or corrosion.
- Verify the 12V battery is fully charged, as low voltage can trigger false codes.
- Look for obvious vacuum leaks or cracked hoses under the hood.
How to Diagnose
Common Mistakes
A very common mistake when diagnosing the P0108 code is automatically replacing the sensor or component mentioned in the code description without first testing it. Electrical issues, wiring damage, or vacuum leaks are frequently the true cause. Always use a multimeter and live data scanner to verify component failure before spending money on parts.
Frequently Asked Questions
Can I drive with the P0108 code?
If the check engine light is solid, you can usually drive to a safe location or mechanic. If the light is flashing, pull over immediately to prevent catastrophic engine or catalytic converter damage.
Will the P0108 code clear itself?
Once the underlying problem is fixed, the engine computer will run its self-checks. If it passes over several drive cycles, the light will turn off automatically. You can also clear it immediately using an OBD2 scanner.
Will this code fail an emissions test?
Yes. If the Check Engine Light is on due to the P0108 code, your Mazda will automatically fail an OBD2 plug-in emissions or smog test.
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Repair Estimate
DIY Difficulty
Can usually be performed at home with basic hand tools.