What is SPN 520355 FMI 20 & How to Solve It?

Discover what SPN 520355 FMI 20 means, its causes, and how to fix it. Follow our simple guide to resolve the issue and get your equipment running smoothly.

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Table of Content

What is SPN 520355 FMI 20:

SPN 520355 FMI 20 indicates a high voltage condition in the Fuel Pressure Sensor Circuit. FMI 20 suggests that the ECM has detected an unusually high voltage coming from the fuel pressure sensor, which can cause inaccurate fuel pressure readings, leading to fuel delivery problems and potential engine performance issues.

Why This Happens:

  • Faulty fuel pressure sensor.
  • Short circuit or wiring issue in the sensor circuit.
  • High voltage supply or power irregularities.
  • Corroded or loose sensor connectors.
  • ECM failure to correctly interpret the sensor signal.

How to Fix It:

  1. Inspect the fuel pressure sensor for visible damage or malfunction.
  2. Check the wiring and connectors for signs of shorts, damage, or corrosion.
  3. Test the sensor’s voltage to ensure it is within the manufacturer’s specified range.
  4. Replace the fuel pressure sensor if it is providing an incorrect signal.
  5. Inspect the ECM to ensure proper communication with the fuel pressure sensor.

How to Avoid It Before It Happens:

  • Regularly inspect fuel system sensors and wiring for damage.
  • Ensure that the voltage supply to the sensor remains stable and within specification.
  • Clean connectors and keep them free from moisture and corrosion.
  • Perform routine diagnostic checks to ensure accurate sensor readings.
  • Clue’s Fuel Management services can help you monitor fuel pressure levels and detect problems before they impact performance.

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