Air Intake Restriction Gauge
Optional instruments are not found on every vehicle. They are stand-alones, not driven by the instrument cluster, and are usually located on the auxiliary dash panel.
The intake-air restriction indicator measures the vacuum on the engine side of the air cleaner at the air cleaner outlet. See Fig.. On standard installations, it is mounted on the intake air piping in the engine compartment.
Fig. 1, Air Intake Restriction Gauge
Air intake restriction vacuum is measured in inches of water (inH2O). For vehicles equipped with a graduated indicator or a restriction gauge on the dash, check the gauge with the engine off. If the yellow signal stays locked in the red zone once the engine is shut down, or is at or above the maximum restriction value in Table., replace the air cleaner element.
Note: Rain or snow can wet the filter and cause a temporarily higher than normal reading.
Table 1, Air Intake Maximum Restriction Values (inH2O)
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Air Intake Maximum Restriction Values (inH2O) |
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Engine Make |
EPA07 and EPA10 Engines |
GHG14, GHG17, and GHG21 Engines |
|
Cummins |
25 |
25 |
|
Detroit |
22 |
18 |