Intake Manifold 1 Pressure Sensor Circuit – Voltage Above Normal or Shorted to High Source
|Fault Code: 122
Intake Manifold 1 Pressure Sensor Circuit – Voltage Above Normal or Shorted to High Source. High signal voltage detected at the intake manifold pressure circuit.
Derate in power output of the engine.
ISX – Intake Manifold 1 Pressure Sensor
ISM – Intake Manifold 1 Pressure Sensor
The electronic 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. The ECM will detect a low signal voltage at operating conditions such as during an idle or a deceleration. The ECM will detect a high signal voltage during high engine load operating conditions.
The intake manifold pressure sensor is located in the air intake horn. Refer to Procedure 100-002 in Section E.
Conditions for Running the Diagnostics
This diagnostic runs continuously when the keyswitch is in the ON position.
Conditions for Setting the Fault Codes
The ECM detects that the intake manifold pressure signal voltage is greater than 4.91-VDC for more than 1 second.
Action Taken When the Fault Code is Active
- The ECM illuminates the amber CHECK ENGINE light immediately when the diagnostic runs and fails.
- A default value of the intake manifold pressure reading is used.
Conditions for Clearing the Fault Code
The ECM will turn off the amber CHECK ENGINE light immediately after the diagnostic runs and passes.
Verify the electronic control module (ECM) calibration is correct. Check the calibration revision history found on QuickServe™ Online for applicable fixes to the calibration stored in the ECM. If necessary, calibrate the ECM. Refer to Procedure 019-032 in Section 19.
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 122, check for multiple faults.
Possible causes of this fault code include:
- Open return circuit in the engine harness, connectors, or sensor
- Signal wire shorted to sensor supply or battery voltage.