Driver Controls and Instruments 10/01/98 f601437a Fig. 3.20, Air Pressure Gauge 10/01/98 f601438a NOTE: Avoid opening the air cleaner and disturb- ing the seals or filter element until the yellow sig- nal stays locked at or above the value shown in Table 3.3 . When this occurs, the air cleaner needs replacing; however, immediate engine shutdown is not necessary. Fig. 3.21, Fuel Gauge Intake-Air Restriction Engine Model * Service at or Above Cummins 25 inH 2 O * Turbocharged engines must be checked at full load and governed engine speed. Table 3.3, Intake-Air Restriction 3.16