What is SPN 676 FMI 5 & How to Solve It?

What is SPN 676 FMI 5

SPN 676 refers to the Intake Manifold Temperature sensor, while FMI 5 indicates that the sensor is reporting a current that’s too low, which usually means open circuit or broken wiring.

Combined, SPN 676 FMI 5 tells you that the engine control module isn’t receiving a proper signal from the intake manifold temperature sensor. Without accurate readings, the system can’t properly manage air-fuel mixture, potentially reducing performance and increasing emissions.

‍

Why This Happens

This fault is most commonly caused by:

• A disconnected or damaged intake manifold temperature sensor.
• Broken or corroded wiring leading to the sensor.
• Faulty connector or loose pins.
• A failed sensor that is no longer sending data.
• Occasionally, ECM-related signal interpretation issues.

‍

How to Fix It

Start by addressing the electrical components:

1. Inspect the sensor and make sure it's properly plugged in.
2. Check the connector pins for corrosion or looseness.
3. Trace the wiring back to the ECM to look for cuts or damage.
4. Replace the sensor if wiring and connectors check out.
5. If the problem persists, test voltage at the ECM and replace the control unit only if needed.
6. Clear the code and recheck to confirm resolution.

‍

How to Avoid It Before It Happens

1. Include sensor wiring in your regular inspection checklist.
2. Protect connectors from moisture and debris buildup.
3. Use quality replacement parts that meet OEM standards.
4. Log sensor replacements and wiring repairs for future tracking.
5. Use software like Clue to store sensor health records and flag recurring faults before they cause engine performance issues.