Why is my Navistar Truck showing a high restriction reading?
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jeremy80Aug 5, 2025
A temporary high restriction reading on your Navistar Truck can occur during heavy snow or rain, but it should disappear once the system dries out. If the gauge locks up in the red zone, inspect the elements for damage, reset the gauge, and recheck the reading with the reused element. Also, plugged inlet screens or ducts can cause high restriction. Check the system upstream for debris, damage, or improper installation.
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Cheryl RussoAug 19, 2025
What to do if my Navistar Truck has no restriction reading?
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Cory RuizAug 19, 2025
If your Navistar Truck's gauge shows no restriction reading, several issues could be the cause. First, check for plugged fittings or vacuum lines. Remove the gauge and apply a vacuum until it locks up in the red zone. Reinsert the gauge and hold the reset button. The indicator should fully return unless there's a blockage. A slow return is normal due to the safety filter in the fitting. Also, inspect for leaks in the vacuum line or the gauge itself by applying vacuum and checking for any drop when the end of the line or the gauge connection is closed airtight. Finally, make sure your turbocharged engine is under full load to generate adequate airflow, and visually inspect the air cleaner element for splits.
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