CAT Engine 411 Fault Code: Cylinder #4 Injector fault
Also called Cylinder #4 Injector Fault, Injector Cylinder #4 fault
Cylinder #4 Injector fault · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
CAT fault code 411 (SPN 654 / FMI 11) means the ECM detected an open or short circuit in the cylinder #4 injector circuit while trying to operate that injector. Expect a misfire and low power. If the problem is in the shared common wire, cylinder #4's neighbor cylinder can be affected too.
High severity. The engine keeps running and the ECM keeps trying to fire the injector, but a dead or misfiring cylinder means lost power, rough running, and possible damage if left unaddressed. Diagnose before continued heavy-load operation.
What does CAT Engine error code 411 mean?
Fault code 411 applies to CAT C10, C12, C15, and C16 engines and points to cylinder #4's injector circuit. The ECM commands the injector solenoid to fire, then monitors that circuit for an open condition, a short to ground, or a short to battery voltage. When it sees one of those faults, it logs code 411.
This is an electrical circuit fault, not necessarily a mechanically bad injector. The wiring, connectors, the solenoid inside the injector, or the ECM driver itself could be at fault. Because injectors on these engines share a common return wire in pairs, a problem in that shared wire can knock out two cylinders at once instead of just one.
The ECM does not shut the engine down for this code. It keeps trying to operate the injector after logging the fault, but the injector may simply not fire while the condition is present. The practical result the operator feels is an engine misfire and a noticeable loss of power.
Common causes of 411
- Damaged or corroded connectors and/or wiring in the injector circuit
- A problem in the engine wiring harness, including a short in the injector harness or a harness short to ground
- A fault in the injector solenoid itself
- A faulty or worn injector that needs replacement
- A mechanical problem in the cylinder itself, separate from the electrical circuit
- An intermittent connection or wiring problem that comes and goes
- A faulty ECM, in rarer cases, after the injector and wiring have been ruled out
How to troubleshoot CAT Engine 411: first checks
- Inspect the connectors and wiring at the cylinder #4 injector for corrosion, damage, chafing, or loose pins.
- Check the injector harness for shorts to ground or shorts to battery voltage, and inspect the shared common wire since a fault there can affect two cylinders at once.
- Wiggle-test the harness and connectors with the engine off to look for an intermittent fault that only shows up under vibration or heat.
- Test the injector solenoid circuit for continuity and proper resistance to determine if the solenoid itself has failed.
- Check for the same fault or a misfire on the paired cylinder that shares the common wire with cylinder #4, since that points to a common-wire problem rather than an isolated injector issue.
- If wiring, harness, and solenoid all check out, inspect the injector for a mechanical or internal fault, and consider it a candidate for replacement.
- If the injector and harness both test good, the ECM itself may need further diagnosis or replacement.
How the code clears
No separate clearing step is listed for this code. The ECM logs the code automatically and keeps attempting to operate the injector; once the underlying wiring, solenoid, or injector problem is repaired, the fault should stop being logged on its own. Confirm the fix by clearing the stored code with diagnostic software and watching for it to return.
Affected models and serial ranges
411 appears in our records across 4 CAT Engine models. Match your machine by model and serial number.
| Model | Serial ranges |
|---|---|
| C10 | Serial range not listed in source records |
| C12 | Serial range not listed in source records |
| C15 | Serial range not listed in source records |
| C16 | Serial range not listed in source records |
Frequently asked questions
What does CAT code 411 mean?
It means the ECM found an open circuit or a short circuit (to ground or to battery voltage) in the cylinder #4 injector circuit while trying to fire that injector. It's logged as SPN 654 / FMI 11.
Will code 411 shut down my engine?
No. The ECM logs the code and keeps trying to operate the injector. You'll typically notice an engine misfire and low power rather than a shutdown.
Can this fault affect more than one cylinder?
Yes. Injectors share a common return wire in pairs. If the wiring problem is in that shared common wire, two cylinders can be affected together instead of just cylinder #4.
Is code 411 always a bad injector?
Not necessarily. Possible causes include damaged wiring and connectors, a harness problem, a faulty solenoid, an intermittent connection, a mechanical problem in the cylinder, or a faulty ECM. The injector is only one possible cause among several.
What symptoms should I expect with fault 411?
Expect an engine misfire and noticeable low power. The affected injector may simply stop firing while the fault condition is present.
Which CAT engines use this code?
Code 411 applies to the C10, C12, C15, and C16 engine models.
How do I know if it's the wiring or the injector itself?
Start with the connectors and harness, checking for damage, corrosion, and shorts to ground or battery voltage. If wiring and the solenoid test good, focus on the injector, and if everything electrical checks out, consider the ECM.