What is SPN 101 FMI 15 & How to Solve It?

What is SPN 101 FMI 15:

SPN 101 refers to the Mass Air Flow (MAF) Sensor, and FMI 15 indicates that the signal is valid but higher than normal, which usually means excessive airflow is being detected.

This can throw off air-fuel ratios and cause performance or emissions issues.

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Why This Happens

• Leaking intake manifold or piping.
• Dirty or faulty MAF sensor.
• Turbo overboosting beyond target.
• ECM misreading sensor voltage.
• MAF calibration drift due to heat or age.

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How to Fix It

1. Inspect all intake piping for leaks or disconnected hoses.
2. Clean the MAF sensor with appropriate cleaner.
3. Test sensor voltage against spec using diagnostics.
4. Replace the MAF sensor if it continues to read high.
5. Clear the code and monitor air/fuel response.

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How to Avoid It Before It Happens

1. Clean or replace MAF sensors on a regular interval.
2. Check clamps and hoses during all PM inspections.
3. Watch for signs of turbo overboost and address early.
4. Don’t ignore changes in fuel economy or idle quality.