Cummins X12 CM2350 X119B (2018 & Newer) Fault Code: 1848 PID: P105 SPN: 105 FMI: 10/10 Intake Manifold 1 Temperature – Abnormal Rate of Change

Lamp:
Amber

Reason:
The intake manifold pressure sensor is reading an erratic value.

Effect:
Possible reduced engine performance.

Circuit Description:
The Engine Control Module (ECM) provides 5 volts to the intake manifold temperature signal circuit, and monitors the change in voltage caused by changes in the resistance of the sensor to determine the intake manifold temperature. When the intake air is cold, the sensor (or thermistor) resistance is high. The ECM signal voltage only pulls down a small amount through the sensor to a ground. Therefore, the ECM senses a high signal voltage or low temperature. When the intake air is warm, the sensor resistance is low. The signal voltage pulls down a large amount. Therefore, the ECM senses a low signal voltage, or a high temperature.

Component Location:
The intake manifold 1 pressure/temperature sensor is located in the air intake manifold.

Conditions for Running the Diagnostic:
1. This diagnostic runs when the keyswitch is turned ON and before engine speed is detected.
2. The engine must be turned OFF for period of 8 hours before this diagnostic will run. This diagnostic runs when the keyswitch is turned to the ON position after an 8 hour cold soak.

Conditions for Setting the Fault Codes:
The Engine Control Module (ECM) detected the engine intake manifold temperature sensor reading was higher or lower than the other temperature sensors on the engine after an extended period of engine OFF time.

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 intake manifold temperature reading.
3. Diesel exhaust fluid injection into the aftertreatment system is disabled.
4. Active and stationary regeneration of the diesel particulate filter will be disabled.
5. Exhaust Gas Recirculation (EGR) valve operation will be disabled.
6. 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, the engine must be shut down with the keyswitch in the OFF position for 8 hours. After the 8 hour cold soak, start the engine and let it idle for 1 minute.
2. The fault code status displayed by the recommended diagnostic tool or equivalent will change to inactive immediately after the diagnostic runs and passes.
3. 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.
4. 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. In-range malfunction of the engine intake manifold temperature sensor.
2. High resistance in the engine intake manifold temperature sensor signal or return lines.