Overview
| CODE | REASON | EFFECT |
| Fault Code: 123 PID: P102 SPN: 102 FMI: 4/4 LAMP: Amber SRT: |
Low signal voltage or open circuit detected in the intake manifold pressure sensor circuit.
|
Possible reduced engine performance.
|
Circuit Description
The engine control module (ECM) provides a 5 volt supply to the intake manifold pressure sensor on the sensor supply circuit. The ECM also provides a ground on the sensor return circuit. The intake manifold pressure sensor provides a signal to the ECM on the intake manifold pressure sensor signal circuit. This sensor signal voltage changes based on the pressure in the intake manifold.
Component Location
The intake manifold 1 pressure/temperature sensor is located in the air intake manifold.
Conditions for Running the Diagnostics
This diagnostic runs continuously when the keyswitch is in the ON position or when the engine is running.
Conditions for Setting the Fault Codes
The Engine Control Module (ECM) detected the intake manifold pressure sensor signal voltage is out of range low.
Action Taken When the Fault Code is Active
- The ECM illuminates the amber CHECK ENGINE lamp and/or the malfunction indicator lamp (MIL) immediately when the diagnostic runs and fails.
- A default value of the intake manifold pressure reading is used.
- Diesel exhaust fluid injection into the aftertreatment system is disabled.
- Active and stationary regeneration of the diesel particulate filter will be disabled.
- Exhaust gas recirculation (EGR) valve operation will be disabled.
- 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
- To validate the repair, perform a key cycle, start the engine and let it idle for 1 minute.
- The fault code status displayed by the recommended Cummins® electronic service tool or equivalent will change to INACTIVE immediately after the diagnostic runs and passes.
- The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
- 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.
- The “Reset All Faults” command in the recommended Cummins® electronic service tool or equivalent can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.
Shop Talk
The intake manifold pressure sensor shares supply and return wires in the engine harness with other sensors. Opens and shorts in the engine harness can cause multiple fault codes to be active. Before troubleshooting Fault Code 123, check for multiple faults.
Possible causes of this fault code include:
- Signal circuit open or shorted to ground in the engine wiring harness or sensor.
- Supply wire open or shorted to ground.
- Malfunctioning intake manifold pressure/temperature sensor
Troubleshooting Summary
Solution: S00006545
Verification
Conditions
- Turn keyswitch ON.
- Connect the recommended Cummins® electronic service tool or equivalent.
Action
- Use the recommended Cummins® electronic service tool or equivalent to read the fault codes.
Specification
Before troubleshooting this fault code, troubleshoot any fault code that is active or has more than one inactive count within the last 25 engine operating hours from the following list:
- Sensor supply 1: 352, 386
Linked Solutions
- None
Repair
- Perform a search on the appropriate fault codes.
Validation
- None
Solution: S00000457
Verification
Conditions
- Turn keyswitch OFF.
- Disconnect the intake manifold pressure/temperature sensor from the engine wiring harness.
Action
- Inspect the pins and connectors for damage.
- Turn keyswitch ON.
- Measure the voltage between the intake manifold pressure sensor SUPPLY pin and the intake manifold pressure sensor RETURN pin at the sensor connector of the engine wiring harness.
- Refer to the circuit diagram or wiring diagram for connector pin identification.
Specification
- Proceed to the Linked Solutions section if voltage is not within the following specification: 4.75 – 5.25 VDC
Repair
- No additional action is required for this solution.
Validation
- None
Solution: S00000758
Verification
Conditions
- Turn keyswitch OFF.
- Disconnect the engine wiring harness connector from the ECM.
- Turn keyswitch ON.
Action
- Inspect the pins and connectors for damage.
- Measure the voltage between the intake manifold pressure/temperature sensor SUPPLY pin and the intake manifold pressure/temperature sensor RETURN pin at the ECM.
- Refer to the circuit diagram or wiring diagram for connector pin identification.
Specification
- A malfunctioning ECM has been detected if voltage at the ECM connector is not within the following specification: 4.75 – 5.25 VDC
- A malfunctioning engine wiring harness has been detected if voltage at the ECM connector is within the following specification: 4.75 – 5.25 VDC
Linked Solutions
- None
Repair
Repair or replace only the components that were found to be out of specification.
- Replace the ECM.
- Repair or replace the engine wiring harness.
Validation
- Connect all components
- Connect the recommended Cummins® electronic service tool or equivalent.
- Disable the fault code.
- Operate the engine within the “Conditions for Clearing the Fault Code” found in the Overview section of the troubleshooting procedure.
- Verify that the fault code is no longer active.
- Check ECM Calibration Revision History
- Use the recommended Cummins® electronic service tool or equivalent to find the current ECM code and revision number in the ECM.
- Compare the ECM code and revision number in the ECM to the calibration revisions listed in the ECM Calibration Revision History Database for applicable changes related to this fault code.
- Refer to ECM Calibration Revision History Database.
Solution: S00000352
Verification
Conditions
- Turn keyswitch OFF.
- Disconnect the intake manifold pressure/temperature sensor from the engine wiring harness.
Action
- Inspect the pins and connectors for damage.
- Place a jumper wire between the intake manifold pressure sensor SUPPLY pin and the intake manifold pressure sensor SIGNAL pin at the sensor connector of the engine wiring harness.
- Refer to the circuit diagram or wiring diagram for connector pin identification.
- Turn keyswitch ON.
- Connect the recommended Cummins® electronic service tool or equivalent.
- Wait 30 seconds before checking the circuit response.
- Use the recommended Cummins® electronic service tool or equivalent to read the fault codes.
Specification
- A malfunctioning intake manifold pressure sensor 1 has been detected if the following fault code became active with the jumper wire in place: 122
Linked Solutions
- None
Validation
- Connect all components
- Connect the recommended Cummins® electronic service tool or equivalent.
- Disable the fault code.
- Operate the engine within the “Conditions for Clearing the Fault Code” found in the Overview section of the troubleshooting procedure.
- Verify that the fault code is no longer active.
- Check ECM Calibration Revision History
- Use the recommended Cummins® electronic service tool or equivalent to find the current ECM code and revision number in the ECM.
- Compare the ECM code and revision number in the ECM to the calibration revisions listed in the ECM Calibration Revision History Database for applicable changes related to this fault code.
- Refer to ECM Calibration Revision History Database.
Solution: S00002392
Verification
Conditions
- Turn keyswitch OFF.
- Disconnect the engine wiring harness connector from the ECM.
Action
- Inspect the pins and connectors for damage.
- Place a jumper wire between the intake manifold pressure sensor SUPPLY pin and the intake manifold pressure sensor SIGNAL pin at the ECM.
- Refer to the circuit diagram or wiring diagram for connector pin identification.
- Turn keyswitch ON.
- Connect the recommended Cummins® electronic service tool or equivalent.
- Wait 30 seconds before checking the circuit response.
- Use the recommended Cummins® electronic service tool or equivalent to read the fault codes.
Specification
- A malfunctioning ECM has been detected if the following fault code does not become active with the jumper wire in place: 122
- A malfunctioning engine wiring harness has been detected if the following fault code became active with the jumper wire in place: 122
Linked Solutions
- None
Repair
Repair or replace only the components that were found to be out of specification.
- Replace the ECM.
- Repair or replace the engine wiring harness.
Validation
- Connect all components
- Connect the recommended Cummins® electronic service tool or equivalent.
- Disable the fault code.
- Operate the engine within the “Conditions for Clearing the Fault Code” found in the Overview section of the troubleshooting procedure.
- Verify that the fault code is no longer active.
- Check ECM Calibration Revision History
- Use the recommended Cummins® electronic service tool or equivalent to find the current ECM code and revision number in the ECM.
- Compare the ECM code and revision number in the ECM to the calibration revisions listed in the ECM Calibration Revision History Database for applicable changes related to this fault code.
- Refer to ECM Calibration Revision History Database.
Solution: S00000443
Verification
Conditions
- Connect all components.
- Turn keyswitch ON.
- Connect the recommended Cummins® electronic service tool or equivalent.
Action
- Use the recommended Cummins® electronic service tool or equivalent to read the fault codes.
- Use the recommended Cummins® electronic service tool or equivalent to find the current ECM code and revision number in the ECM.
- Compare the ECM code and revision number in the ECM to the calibration revision listed in the ECM calibration revision history for applicable changes.
Specification
- If a calibration update for this fault code is available, the ECM calibration revision must be that revision or higher.
Linked Solutions
- None
Repair
- Prior to downloading the ECM calibration, check to see that all job images and all other troubleshooting has been documented as downloading an ECM calibration will remove the fault codes on the ECM.
- Download the updated ECM calibration code.
Validation
- Connect all components
- Connect the recommended Cummins® electronic service tool or equivalent.
- Disable the fault code.
- Operate the engine within the “Conditions for Clearing the Fault Code” found in the Overview section of the troubleshooting procedure.
- Verify that the fault code is no longer active.
- Check ECM Calibration Revision History
- Use the recommended Cummins® electronic service tool or equivalent to find the current ECM code and revision number in the ECM.
- Compare the ECM code and revision number in the ECM to the calibration revisions listed in the ECM Calibration Revision History Database for applicable changes related to this fault code.
- Refer to ECM Calibration Revision History Database.
If all steps have been completed and no root cause has been identified, then follow the technical escalation process.