QSK CM2358 Fault Code 123 Intake Manifold 1 Pressure Sensor Circuit – Voltage Below Normal or Shorted to Low Source.Low signal voltage or open circuit detected in the intake manifold pressure sensor circuit.Possible reduced engine performance.
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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 pressure sensor 1 is located in intake manifold 1.
Conditions for Running the Diagnostics
This diagnostic runs continuously when the keyswitch is in the ON position.
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 immediately when the diagnostic runs and fails. A default value of the intake manifold pressure reading is used.
Conditions for Clearing the Fault Code
Turn the keyswitch OFF. Allow the ECM to completely power down and turn the keyswitch ON.
The fault code status displayed by the recommended 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.
The “Reset All Faults” command in the recommended electronic service tool or equivalent can be used to clear active and inactive faults.
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.
A malfunctioning intake manifold pressure sensor
