SPN 655 — Injector Cylinder #05
System: Fuel
Circuit or performance fault for the cylinder 5 fuel injector.
Can I keep running it?
HIGH — limit use, diagnose now
Misfire and rough running are likely. Avoid heavy load; a stuck or leaking injector can wash down the cylinder or dilute the oil.
Likely causes
- Injector solenoid circuit open or shorted
- Chafed harness or loose terminal nut under the valve cover
- Worn, sticking or leaking injector
- Connector (feed) tube or seal problem
- ECM injector driver fault
Checks & fixes (easiest first)
- Check the FMI — open/short FMIs point to wiring and the coil first
- Read balance rates and run a cylinder cutout / contribution test
- Measure injector return flow, isolating cylinder 5 per the OEM procedure
- Inspect the harness under the valve cover and check oil level for fuel dilution
Common FMIs with SPN 655
- SPN 655 FMI 2Data erratic, intermittent, or incorrect
- SPN 655 FMI 5Current below normal or open circuit
- SPN 655 FMI 6Current above normal or grounded circuit
- SPN 655 FMI 7Mechanical system not responding or out of adjustment
Related codes
- SPN 651Injector Cylinder #01
- SPN 157Injector Metering Rail 1 Pressure (Fuel Rail)
- SPN 1322Engine Misfire for Multiple Cylinders
Troubleshooting guides
FAQ
What does SPN 655 mean?
SPN 655 is Injector Cylinder #05. Circuit or performance fault for the cylinder 5 fuel injector.
Can I keep running with SPN 655?
Misfire and rough running are likely. Avoid heavy load; a stuck or leaking injector can wash down the cylinder or dilute the oil.
What causes SPN 655?
Injector solenoid circuit open or shorted; Chafed harness or loose terminal nut under the valve cover; Worn, sticking or leaking injector; Connector (feed) tube or seal problem; ECM injector driver fault.