| Tools Needed | Quantity | |
| 1U-5470 Engine Pressure Group | 1 | |
Absolute pressure - Absolute pressure is the gauge pressure plus the local barometric pressure.
Gauge pressure - Gauge pressure is the absolute pressure minus the local barometric pressure.
The inlet manifold pressure sensor measures the absolute inlet manifold air pressure.
To verify that the inlet manifold pressure sensor is accurate, use the Caterpillar Electronic Technician (ET) to read the inlet manifold air pressure when the engine is stopped. The correct pressure will be the ambient barometric pressure.
Use the following procedure to verify that the inlet manifold pressure sensor is correct.
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| Illustration 1 | g06264991 |
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(1) Intake manifold temperature sensor at cylinder 1.
(2) Intake manifold plug (3) Intake manifold pressure sensor | |
Remove one of the plugs from the air inlet manifold. Connect a line from the opening to a pressure gauge from the 1U-5470 Engine Pressure Group. Operate the engine under a load. Use Cat ET to read the inlet manifold air pressure. Read the pressure gauge from the 1U-5470 Engine Pressure Group and add the local barometric pressure to the reading. Compare the calculation to the reading from Cat ET.