Cummins X12 CM2350 X119B (2018 & Newer) Fault Code: 7864 PID: SPN: 1209 FMI: 10/10 Exhaust Gas Pressure – Abnormal Rate of Change

Lamp:
Amber

Reason:
The exhaust gas pressure sensor is reading an erratic value.

Effect:
Possible reduced engine performance.

Circuit Description:
The exhaust gas pressure sensor is used to measure exhaust gas pressure in the exhaust manifold. This information is used by the Engine Control Module (ECM) to control emissions and Exhaust Gas Recirculation (EGR) valve operation. The ECM provides a 5 volt supply to the exhaust gas pressure sensor on the sensor supply circuit. The ECM also provides a ground on the sensor return circuit. The exhaust gas pressure sensor provides a signal to the ECM on the exhaust gas pressure sensor signal circuit. This sensor signal voltage changes, based on the pressure in the exhaust manifold.

Component Location:
The exhaust gas pressure sensor is located above the front section of the exhaust manifold and is plumbed into the exhaust manifold.

Conditions for Running the Diagnostic:
This diagnostic runs immediately after the keyswitch is turned OFF, and the engine coolant temperature is above 70°C or 158 °F.

Conditions for Setting the Fault Codes:
The Engine Control Module (ECM) detected the exhaust pressure reading was higher or lower than the other absolute pressure sensors when the keyswitch is OFF and the engine is not running.

Action Taken When the Fault Code is Active:
1. The ECM illuminates the amber check engine lamp and/or the Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.
2. A default value is used for the exhaust gas pressure sensor reading.
3. Exhaust Gas Recirculation (EGR) valve operation will be disabled.
4. Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.

Conditions for Clearing the Fault Code:
1. To validate the repair, first ensure the engine coolant temperature is above 70°C or 158°F. Operate the engine if necessary.
2. Cycle the keyswitch to the ON position for 30 seconds, then cycle the keyswitch to the OFF position for 30 seconds. Start the engine and run it at high idle for up to 5 minutes.
3. The fault code status displayed by the recommended diagnostic tool or equivalent will change to inactive immediately after the diagnostic runs and passes.
4. The ECM will turn off the amber check engine lamp immediately after the diagnostic runs and passes.
5. For On-Board Diagnostics (OBD) engines, the ECM will extinguish the Malfunction Indicator Lamp (MIL) after three consecutive trips where the diagnostic runs and passes.
6. The “reset all faults” command in the recommended diagnostic tool or equivalent can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications

Shop Talk:
Possible causes of this fault code include:
1. Stuck in-range exhaust gas pressure sensor reading.
2. High resistance in the exhaust gas pressure sensor signal or return lines.
3. Plugging or restriction in the exhaust gas pressure sensor tube.
4. Leaks in the exhaust system.