Checking the Air Cleaner Filter Minder Gauge

The filter minder gauge measures the amount of air restriction (in inches or millimeters of water vacuum) in the air intake system. It is connected to the air intake tube by a vacuum hose and a small vacuum filter. The gauge takes its measurements when the engine is running at full load, and then locks in place until reset. See Fig. or Fig. as applicable to the vehicle, for depictions of how the indicator appears when the air intake is partially restricted and when it is fully restricted and should be replaced.

Partial Restriction

Full Restriction

Fig. 1, Air Restriction Indicator, Cummins Diesel Engines

Partial Restriction

Full Restriction

Fig. 2, Air Restriction Indicator, Gasoline and Detroit Diesel Engines