Case IH 19664 – Engine Control Module (ECM): Intake Manifold Pressure is Too High

The engine control system has detected that the air pressure entering the intake manifold exceeds the maximum allowable physical limit for the current operating conditions. This can be caused by an actual overboost condition (such as a stuck turbocharger wastegate) or an electrical fault causing the intake manifold pressure sensor to report an artificially high voltage reading.

• Tier 4b
• Maxxum
• Puma
• Magnum
• Steiger
• N-series tractor loader backhoes (TLBs)

1. 1

   Perform a sensor plausibility check by monitoring the intake manifold pressure sensor live data with the key on and engine off (should read normal atmospheric pressure)

2. 2

   Inspect the wiring harness (B-9001) and connectors for the intake manifold pressure sensor for shorts to battery, open circuits, or damaged pins

3. 3

   If the sensor reads correctly at rest but spikes under load, inspect the turbocharger wastegate actuator and boost pressure modulator valve for mechanical overboost

4. 4

   Check the intake ducting and boost pressure accumulator for any blockages or restrictions

1. 1

   Confirm fault code

   Connect the CNH Electronic Service Tool (EST) to the machine's diagnostic port to confirm fault code 19664 is active.

2. 2

   Inspect sensor connector

   Disconnect the intake manifold pressure sensor and inspect the connector for moisture, corrosion, or pushed-back pins. Clean or repair the connector as necessary.

3. 3

   Test wiring harness

   Use a multimeter to test the sensor's wiring harness back to the Engine ECU for continuity and ensure there is no short to voltage.

4. 4

   Replace sensor

   If the wiring is intact and the sensor reading is implausible, remove and replace the intake manifold pressure sensor.

5. 5

   Inspect overboost components

   If the sensor is functioning correctly but the engine is physically overboosting, inspect the boost pressure modulator valve (mounted near the thermostat housing) and the turbocharger wastegate. Replace the modulator valve or free up/replace the wastegate actuator if they are binding.

6. 6

   Reassemble and test

   Reassemble all components, clear the fault codes using the diagnostic tool, and test run the machine under load to verify the intake manifold pressure remains within specified limits and the code does not return.