What is SPN 168 FMI 4
- SPN 168: Refers to a fault related to the fuel pressure sensor, indicating that the fuel pressure in the system is outside the expected range.
- FMI 4: Indicates that the signal from the fuel pressure sensor is below the expected value, meaning the ECM is receiving a lower-than-expected signal from the sensor, which can affect fuel delivery and engine performance.
Together, SPN 168 FMI 4 signals a problem with the fuel pressure sensor or the fuel system, possibly due to low fuel pressure or malfunctioning components.
Why It Happened
This fault code is commonly caused by:
- A malfunctioning fuel pressure sensor that is not providing accurate data to the ECM.
- A faulty fuel pump that is not maintaining the correct fuel pressure.
- Blockages or restrictions in the fuel lines that affect pressure readings.
- Wiring issues between the sensor and ECM, causing incorrect or inconsistent signals.
- Fuel filter clogging or fuel system contamination affecting fuel pressure.
How to Resolve It
To resolve SPN 168 FMI 4:
- Inspect the fuel pressure sensor: Check the sensor for damage or malfunction, and replace it if necessary.
- Check the fuel pump: Ensure that the fuel pump is functioning correctly and providing proper pressure.
- Inspect the fuel system: Check for any blockages or restrictions in the fuel lines.
- Check wiring and connections: Inspect the wiring between the fuel pressure sensor and ECM for damage, wear, or poor connections.
- Clear the fault code: After repairs, clear the fault code and restart the engine to ensure the issue is fixed.
How to Avoid Before It Happens
To prevent SPN 168 FMI 4:
- Regularly inspect the fuel system, including the pressure sensor and fuel pump.
- Replace fuel filters periodically to ensure smooth fuel flow and avoid contamination.
- Use Clue to monitor fuel pressure data and get real-time alerts when pressure readings fall outside the normal range.
