Cummins ISB CM550 (1990-94) Fault Code: 122 PID: 102 SPN: 102 FMI: 3 Intake Manifold Pressure Sensor Circuit

Posted by PerDiezel Solutions on January 16, 2026

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

Component Location
The intake manifold pressure sensor is located on the rear of the intake air manifold in the
second port on the side of the head to the right of the fuel filter.

Shop Talk
1) Determine if engine is being overfueled.
2) Confirm that the correct intake manifold pressure sensor part number is being used.
3) Confirm that the correct turbocharger is being used.
4) If it is suspected that cold intake air is the cause of the high intake manifold pressure, test
the engine with warm intake air.
5) 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.

Cummins ISB CM550 (1990-94) Fault Code: 115VP44 PID: 190 SPN: 190 FMI: 2 Engine Speed Sensor (ESS) Circuit

Cummins ISB CM550 (1990-94) Fault Code: 115VP30 PID: 190 SPN: 190 FMI: 2 Engine Speed Sensor (ESS) Circuit

Cummins ISB4.5 CM2150 Fault Code: 111 PID: 629 FMI:12 Engine Control Module Critical Internal Failure – Bad Intelligent Device or Component

Cummins ISB4.5 CM2150 Fault Code: 4948 PID: SPN: 6874 FMI: 3 Performance Bias Selection Switch Circuit – Voltage Above Normal or Shorted to High Source.

Cummins ISB4.5 CM2150 Fault Code: 4769 PID: SPN: 1761 FMI: 11 Aftertreatment 1 Diesel Exhaust Fluid Tank Level Sensor – Root Cause Not Known.

Cummins ISB4.5 CM2150 Fault Code: 4739 PID: SPN: 1761 FMI: 11 Aftertreatment 1 Diesel Exhaust Fluid Tank Level Sensor – Root Cause Not Known.

WARNING!