Cummins fault code 1657
Engine Misfire Cylinder 4: condition exists
What it means
Cummins' description: Engine Misfire Cylinder 4 - Condition Exists.
SPN 1326 is Engine Misfire Cylinder #4. FMI 31 means the ECM has confirmed the condition described in the code is happening.
Each cylinder has an electronically controlled fuel injector. The ECM watches each injector's circuit and how each cylinder is contributing, and flags misfires or fueling errors.
What the lamp means
An amber (yellow) warning lamp means the engine can usually keep running, but the fault should be repaired soon, ideally the same day.
Green, yellow, red: three ways this can look
The same code can be a quick fix or a reason to shut down. Match your situation to the closest example.
Keep an eye on it
A single injector or misfire code that cleared and the engine runs smooth.
Schedule a repair
Rough running, smoke, or a misfire or injector code that keeps coming back. Schedule diagnosis. A bad injector can wash down a cylinder and hurt fuel economy.
Stop and get help
Heavy knocking, a severe miss, a red lamp, or smoke pouring out. Shut it down. A stuck-open injector can hydrolock or melt a piston.
Common causes
The sensor reading itself is out of range or the condition is real, so look at the system:
- Worn or sticking injector
- Low compression in that cylinder
- Fuel supply or rail pressure problem
- Air in the fuel
What you can check before calling
- Note rough idle, shaking, white or black smoke, or a knocking sound
- Check whether the misfire is constant or only cold
- Check recent fuel filter service and fuel quality
Clearing the code without fixing the cause usually brings it right back, and on emissions systems it can restart derate timers.
Engines and sources
Listed by Cummins for: QSB 6.7, QSL 9, QSB 4.5, QSF 3.8. Cummins uses the same fault code numbers across its electronic engines, including on-highway models like the ISB/B6.7, ISL/L9 and ISX/X15, though not every code applies to every engine or software level. Source: Cummins Tier 4 Fault Codes. Always confirm with Cummins service information (QuickServe) for your engine serial number.
Related Injectors and misfire codes
- 1656 SPN 1325 FMI 31
Engine Misfire Cylinder 3: condition exists - 1658 SPN 1327 FMI 31
Engine Misfire Cylinder 5: condition exists - 1655 SPN 1324 FMI 31
Engine Misfire Cylinder 2: condition exists - 1659 SPN 1328 FMI 31
Engine Misfire Cylinder 6: condition exists - 1654 SPN 1323 FMI 31
Engine Misfire Cylinder 1: condition exists - 1622 SPN 659 FMI 5
Injector Solenoid Driver Cylinder 9 Circuit: circuit open / current low
Look up another code
Cummins fault code (like 1922), J1939 SPN and FMI (like SPN 3251 FMI 0), or an OBD-II code (like P0420).
Questions
What does Cummins fault code 1657 mean?
Cummins fault code 1657 is J1939 SPN 1326 FMI 31: Engine Misfire Cylinder 4 - Condition Exists. In plain terms: engine misfire cylinder 4: condition exists.
Can I keep driving with Cummins code 1657?
Usually for a short time, if the engine runs normally and no other warnings are on. Get it diagnosed soon, because many amber codes lead to a derate if ignored. Look at the green, yellow and red examples on this page to judge your situation.
What is the SPN and FMI for Cummins code 1657?
SPN 1326 identifies the part or system (Engine Misfire Cylinder #4). FMI 31 describes the type of failure: condition exists.
What usually causes Cummins code 1657?
The most common causes are: worn or sticking injector; low compression in that cylinder; fuel supply or rail pressure problem.
Diesel down in the Midlands?
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