Cummins X15 CM2450 X124B (2018 & Newer) Fault Code: 1657 PID: SPN: 1326 FMI: 31 Engine Misfire Cylinder 4- Condition Exists

Circuit Description
An algorithm in the ECM calibration monitors engine speed as each injector fires. If a cylinder(s) has high or low contribution to engine speed, the fault will become active. The intention of the fault is to assist in troubleshooting performance complaints such as engine misfire and low power.

Component Location
The ECM mounting location varies, depending on the engine model, and may be mounted either on or off the engine.

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

Conditions for Setting the Fault Codes
The Engine Control Module (ECM) detected a cylinder 4 misfire.

Action Taken When the Fault Code is Active
The ECM illuminates the amber CHECK ENGINE lamp and/or Malfunction Indicator Lamp (MIL) after the diagnostic fails on two consecutive trips.

Exhaust Gas Recirculation (EGR) valve operation will be disabled.
Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.
Conditions for Clearing the Fault Code
To validate the repair, start the engine and let it idle for up to 5 minutes.
The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
For On-Board Diagnostics (OBD) engines, the ECM will extinguish the Malfunction Indicator Lamp (MIL) after three consecutive trips where the diagnostic runs and passes.
The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop Talk
If Fault Code 1657 is inactive in the ECM memory and there is no complaint such as “low power” or “engine misfire”, it is possible that an intermittent event such as air entering the fuel system following a filter change caused the fault. Inactive counts of Fault Code 1657 should be disregarded unless other performance symptoms are present. The engine coolant temperature must be greater than 71°C [160°F] before this diagnostic will run.

Causes of cylinder misfire can include:

Valve lash out of specification (compare actual valve lash to reset limits)
Cylinder malfunction (check for high blowby when the engine is loaded)
Valve malfunction or valve held open (listen for intake valve “chirping” noise in the intake)
Extra, missing, or damaged sealing washer under an injector
Injector malfunctions (“swap” injectors to see if the problem “follows” the indicated injector).

Possible Cause:
1) Cylinder Misfire
2) ECM calibration