Cummins ISB4.5 CM2150 Fault Code: 689 PID: 190 SPN: 190 FMI: 2 Engine Crankshaft Speed/Position – Data Erratic, Intermittent, or Incorrect.

Posted by PerDiezel Solutions on January 20, 2026

Circuit Description
The engine control module (ECM) provides a 5 volt supply to the engine crankshaft speed/position sensor on the sensor supply circuit. The ECM also provides a ground on the sensor return circuit. The crankshaft speed/position sensor provides a signal to the ECM on the crankshaft speed/position sensor signal circuit. This sensor generates a signal to the ECM as the crankshaft speed indicator ring passes the sensor. The ECM interprets this signal into an engine speed reading and determines engine position.

Conditions for Running the Diagnostics
This diagnostic runs continuously when the engine is running.

Conditions for Setting the Fault Codes
The ECM detects a loss of the crankshaft speed/position sensor for more than 1second.

Action Taken When the Fault Code is Active
-The ECM illuminates the amber CHECK ENGINE light and/or the malfunction indicator lamp (MIL) immediately when the diagnostic runs and fails.
-The camshaft speed sensor is used to provide engine speed and position information to the ECM.

Conditions for Clearing the Fault Code
-To validate the repair, start the engine and let it idle for 1 minute.
-The ECM will turn off the amber CHECK ENGINE light immediately after the ECM detects a valid signal from the crankshaft speed/position sensor.
-The ECM will turn off the malfunction indicator lamp (MIL) after three consecutive ignition cycles that the diagnostic runs and passes.
-This fault code and malfunction indicator lamp (MIL) can also be cleared with INSITE™ electronic service tool.

Possible Causes
-Open or short circuit of the 5 volt supply, signal, or return wire in the engine harness
-Damaged or failed engine speed sensor

Cummins ISB4.5 CM2150 Fault Code: 688 PID: SPN: 98 FMI: 0 Engine Oil Level – Data Valid but Above Normal Operating Range – Most Severe Level.

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Cummins ISB4.5 CM2150 Fault Code: 686 PID: 103 SPN: 103 FMI: 2 Turbocharger 1 Speed – Data Erratic, Intermittent, or Incorrect.

Cummins ISB4.5 CM2150 Fault Code: 649 PID: SID 115 SPN: 1378 FMI: 11 Engine Oil Change Interval – Condition Exists.

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Cummins ISB4.5 CM2150 Fault Code: 597 PID: 167 SPN: 167 FMI: 1 Electrical Charging System Voltage – Data Valid But Below Normal Operating Range – Moderately Severe Level.

WARNING!