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

Posted by PerDiezel Solutions on January 16, 2026

Circuit Description
The engine speed sensor provides engine speed information to the engine control module (ECM).
The sensor must be powered up by (+) 5 VDC to operate. The sensor generates its signals by
sensing the movement of target teeth machined into a tone wheel that is mounted to the crankshaft. The tone wheel has 35 teeth and a gap where the 36th tooth would be placed. This missing tooth indicates cylinder 1 and 6 are at top dead center.

Component Location
The engine speed sensor is located on the intake side of the engine block, at crankshaft level,
between cylinders 4 and 5 on ISB and QSB5.9 engine with the Bosch fuel system.

Shop Talk
This fault code will also cause a fuel derate. This could be the cause of a low-power complaint. Also, this fault code can cause starting problems in cold weather.
ISB and QSB engines with the fuel pump system use separate sensors for engine speed and position.

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.

Cummins ISB4.5 CM2150 Fault Code: 4737 PID: SPN: 3031 FMI: 11 Aftertreatment 1 Diesel Exhaust Fluid Tank Temperature – Root Cause Not Known.

WARNING!