Electronic Control System ISM and QSM11 Engines – FAULT CODE 123

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Overview

Intake Manifold Pressure Sensor Circuit SMALL | MEDIUM | LARGE

Circuit Description

The intake manifold pressure sensor monitors intake manifold pressure and passes information to the electronic control module (ECM) through the engine harness. If intake manifold pressure becomes too high, it will cause a derate condition.

Component Location

The intake manifold pressure sensor is located in the air intake manifold toward the front of the engine.

Shop Talk

• Check for high restriction in the intake air manifold due to a shutdown device in the manifold if the vehicle is equipped with one. Do not
  remove this device. If the engine is operated in a flammable atmosphere, the device is an essential safety feature. Removing it can cause severe personal injury or death.
• Check for installation of a torque-limiting device breakout wiring harness. Temporarily remove the torque-limiting device from the engine harness and install the intake manifold pressure sensor directly to the engine harness. If Fault Code 123 becomes inactive, inspect the torque-limiting device.

Refer to Troubleshooting Fault Code t05-123