CAT 47 Fault Code: Engine Injector Cylinder #04 : Not Responding Properly
Engine Injector Cylinder #04 : Not Responding Properly · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
CAT code 47, SPN 654 FMI 7, means the ECM detects that the cylinder #4 injector solenoid is not responding properly even though the ECM keeps energizing it. The code is logged and the engine keeps running, but the injector event should be checked before it causes a misfire, power loss, or engine damage under load.
Medium severity. The engine keeps running and the ECM continues to energize the injector, so this is not an immediate shutdown code. But an unresponsive injector on one cylinder can cause misfire, rough running, or uneven load sharing, especially under heavy load or when warmed up, so it should be diagnosed before extended operation.
What does CAT error code 47 mean?
SPN 654 FMI 7 points to cylinder #4's Electronic Unit Injector (EUI) not behaving the way the ECM expects it to. These engines use EUIs with a solenoid in each injector, and the ECM sends 105 V pulses to each solenoid at a specific time and duration based on engine load and speed. FMI 7 is a 'mechanical fault' or 'not responding properly' type code, meaning the ECM commands the injector but does not see the expected result.
When this code sets, the ECM logs the fault and keeps energizing the injector solenoid normally, it does not shut down or derate the engine for this code by itself. However, an injector that isn't responding correctly can cause a rough-running cylinder, loss of power, or increased wear if left unaddressed.
Problems with an injector solenoid typically show up once the engine is warmed up and/or under vibration from heavy loads, which points toward heat-related or vibration-related wiring and connector issues as much as toward the injector itself.
Common causes of 47
- Failed injector (the solenoid or internal injector components are not responding as commanded)
- Wiring between the ECM and the valve cover has a fault (open, short, corrosion, chafing)
- Wiring under the valve cover for the injector harness has a fault, often only showing up under vibration
- Plugged oil outlet port on the exhaust valve rocker arm
How to troubleshoot CAT 47: first checks
- Bring the engine to normal operating temperature before testing, since injector solenoid problems typically appear once warmed up and/or under load vibration
- Inspect the wiring and connectors between the ECM and the valve cover for damage, corrosion, or loose pins, paying close attention to connections that might only fault under vibration
- Inspect the injector harness wiring under the valve cover for chafing, corrosion, or damaged insulation
- Check the oil outlet port on the exhaust valve rocker arm for the affected cylinder to confirm it is not plugged
- Perform the Fuel System Verification Test as required to properly diagnose and clear this code
How the code clears
The Fuel System Verification Test must be performed to clear a -7 (FMI 7) code. No separate clearing step is listed beyond running this test. Perform the test with the engine at normal operating temperature and pay close attention to wiring and connector condition during the procedure, since intolerant faults may only appear under vibration.
Frequently asked questions
What does CAT fault code 47 mean?
CAT code 47, SPN 654 FMI 7, means the ECM sees that the cylinder #4 injector solenoid is not responding properly to the commands it sends, even though it keeps energizing the injector normally.
Will code 47 shut down my engine?
No. The ECM logs the code and continues energizing the injector solenoid as normal. The code by itself does not force a shutdown, but an unresponsive injector can still cause rough running or power loss.
How do you clear CAT code 47?
You must perform the Fuel System Verification Test to clear a -7 (FMI 7) code. No other reset procedure is listed.
Why does this fault only show up when the engine is warmed up or under load?
Injector solenoid problems, along with wiring and connector faults, often only appear once the engine reaches normal operating temperature and experiences vibration from heavy loads, so testing cold or at idle may not reveal the issue.
What parts should I inspect first for SPN 654 FMI 7?
Check the injector itself, the wiring between the ECM and valve cover, the injector harness wiring under the valve cover, and the oil outlet port on the exhaust valve rocker arm for a plug.
Is a plugged oil port really connected to an injector solenoid fault?
Yes, a plugged oil outlet port on the exhaust valve rocker arm is listed as one of the possible causes for this code, alongside injector and wiring faults.