SPN 107 FMI 2 – Air Filter Sensor plausibility error Fault Code (Symptoms, Causes & Fix)
The SPN 107 FMI 2 fault code is a diesel engine diagnostic trouble code indicating an air filter sensor plausibility error. This code suggests that the Engine Control Module (ECM) has detected an inconsistency in the readings from the air filter differential pressure sensor, which monitors the pressure difference across the air filter to ensure proper airflow.
What SPN 107 FMI 2 Means
The SPN 107 FMI 2 fault code specifically relates to the air filter differential pressure sensor. This sensor is responsible for measuring the pressure drop across the air filter, which helps the ECM determine if the air filter is clogged or functioning correctly. When the ECM receives a signal that doesn't align with expected parameters, it triggers this fault code, indicating a plausibility error.
Common Causes of This Fault Code
- Faulty air filter differential pressure sensor
- Clogged or restricted air filter
- Damaged or disconnected wiring harness
- Corroded or loose electrical connectors
- ECM signal processing issues
Symptoms Drivers May Notice
When the SPN 107 FMI 2 fault code is active, drivers may notice a reduction in engine performance due to restricted airflow. This can manifest as decreased power, increased fuel consumption, or even the activation of the check engine light. In severe cases, the engine may enter a derate mode to prevent damage.
How Technicians Diagnose This Fault
Diagnosing the SPN 107 FMI 2 fault code involves a systematic approach:
- Begin with a visual inspection of the air filter for signs of clogging or damage. Replace the filter if necessary.
- Inspect the wiring harness connected to the air filter differential pressure sensor for any signs of damage, chafing, or disconnection.
- Check electrical connectors for corrosion or looseness and clean or tighten as needed.
- Use a multimeter to verify the sensor's power supply and ground circuits, ensuring proper voltage levels.
- Employ a diagnostic tool to read sensor data and compare it to expected values, confirming the sensor's functionality.
Common Misdiagnosis
Technicians often make the mistake of replacing the air filter without checking the sensor or wiring. Another common error is assuming a sensor fault without verifying the integrity of the wiring harness. Additionally, overlooking connector issues due to a focus on sensor replacement can lead to misdiagnosis.
Can You Keep Driving?
While it may be possible to continue driving with the SPN 107 FMI 2 fault code active, it's not advisable. The fault can lead to reduced engine performance and increased fuel consumption. In some cases, the engine may enter a derate mode, limiting power to prevent further damage. Addressing the issue promptly is recommended to maintain optimal engine performance.
Mechanic's Diagnostic Tip
When diagnosing the SPN 107 FMI 2 fault code, always verify the sensor's power supply and ground circuits before replacing the sensor. This step can prevent unnecessary part replacement and ensure a more accurate diagnosis.
Frequently Asked Questions
- What does SPN 107 FMI 2 indicate? It indicates a plausibility error with the air filter differential pressure sensor.
- Can a clogged air filter trigger this code? Yes, a clogged air filter can cause a pressure drop, leading to this fault code.
- Is it safe to drive with this fault code? It's possible but not recommended, as it can lead to reduced engine performance and potential engine derate.
