What is SPN 676 & How to Solve It?

What is SPN 676:

SPN 676 refers to the Intake Manifold 1 Temperature Sensor. When this code appears (typically with an FMI value), it means the engine is detecting an issue with the air temperature measurement going into the intake manifold.

Without accurate temperature data, the ECM cannot properly manage air-fuel mixture, which affects fuel efficiency and emissions control.

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Why This Happens

• Faulty or degraded intake air temperature sensor.
• Corroded or disconnected sensor wiring.
• Sensor covered in oil or debris.
• Short or open circuit in the harness.
• Sensor response time is out of range.

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How to Fix It

1. Inspect the sensor for contamination or damage.
2. Clean the sensor carefully if it’s dirty but still intact.
3. Test wiring and connectors for continuity and voltage.
4. Replace the sensor if response is slow or readings are off.
5. Clear the code and monitor engine performance.

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How to Avoid It Before It Happens

1. Clean or inspect sensors during every major service.
2. Avoid high-pressure washing near sensor wiring.
3. Use quality replacement sensors rated for your engine model.
4. Protect wiring looms from engine heat and abrasion.

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