This document is a Cummins fault code 433 troubleshooting manual for the intake manifold pressure sensor circuit on ISB CM550 applications. It explains how the ECM monitors intake manifold pressure at idle, where the sensor is located, and how to verify the circuit after repair.
Official Cummins fault code 433 document details
| Brand | Cummins |
|---|---|
| Model coverage | ISB CM550 (1990-94) |
| System/Group | DTCs; Intake Manifold Pressure Sensor Circuit |
| Publication no. | Fault Code 433; PID: P102; FMI: 2 |
| Year/Revision | Unknown; copyright 2017 shown in file extract |
| Pages | 5 |
| File size | 0.5 MB |
| Format | |
| Language | English |
Document table of contents
- FAULT CODE: 433
- PID: P102
- FMI: 2
- INTAKE MANIFOLD PRESSURE SENSOR CIRCUIT
- DESCRIPTION
- COMPONENT LOCATION
- TROUBLESHOOTING STEPS
- Step 1A: inspect the sensor circuit for tampering
- Step 1B: inspect the intake manifold pressure sensor and engine harness connectors
- Step 2A: inspect the engine harness and ECM connectors
- Step 2B: check for a short from pin to pin
- Step 2C: check for a short circuit to ground
- Step 2D: check for an open circuit in the return line
- Step 3A: disable the fault code and verify inactive status
- Step 3B: clear inactive fault codes
Applicable truck models
This file covers Cummins ISB CM550 (1990-94) engine diagnostic fault code information for the intake manifold pressure sensor circuit. The extract identifies the sensor location as the side of the intake manifold, just to the right of the fuel filter, and the diagnostic work centers on the sensor connector, engine harness, ECM connector, pin 45, pin 19, pin B, and engine block ground. For current manufacturer information, visit the Cummins official website.
Who needs this Cummins fault code 433 manual
Use this Cummins fault code 433 manual when an ISB CM550 engine logs a high intake manifold pressure value at idle and derate symptoms or active diagnostics need a circuit-level check. It is intended for mechanics, electrical diagnostic technicians, and workshop owners verifying harness damage, connector condition, resistance values, sensor replacement, and final code clearing with a diagnostic tool.
The procedure starts with visual inspection for external wires, damaged harness braiding, loose connectors, corroded pins, bent or broken pins, pushed back or expanded pins, moisture, damaged seals, dirt, connector shell damage, wire insulation damage, and locking tab damage. Later checks require disconnecting the engine harness from the intake manifold pressure sensor and the ECM, then measuring resistance for shorts and opens. The specified pass/fail limits in the extract include more than 100k ohms for short checks and less than 10 ohms for the return line continuity check. The final verification requires connecting all components, turning the key switch ON, disabling the fault code, idling the engine for 1 minute, confirming Fault Code 433 is inactive, and clearing inactive fault codes.
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