SPN 651 — Injector Cylinder #01
System: Fuel
Circuit or performance fault for the cylinder 1 fuel injector.
Can I keep running it?
HIGH — limit use, diagnose now
Misfire and rough running are likely. Avoid heavy load; a stuck injector can damage the engine.
Likely causes
- Injector solenoid circuit open or shorted
- Damaged harness under the valve cover
- Worn or sticking injector
- ECM driver fault
Checks & fixes (easiest first)
- Run a cylinder cutout / contribution test
- Check injector circuit resistance
- Inspect harness under the valve cover
- Swap injector per OEM procedure if allowed
Common FMIs with SPN 651
- SPN 651 FMI 2Data erratic, intermittent, or incorrect
- SPN 651 FMI 5Current below normal or open circuit
- SPN 651 FMI 6Current above normal or grounded circuit
- SPN 651 FMI 7Mechanical system not responding or out of adjustment
Related codes
- SPN 157Injector Metering Rail 1 Pressure (Fuel Rail)
FAQ
What does SPN 651 mean?
SPN 651 is Injector Cylinder #01. Circuit or performance fault for the cylinder 1 fuel injector.
Can I keep running with SPN 651?
Misfire and rough running are likely. Avoid heavy load; a stuck injector can damage the engine.
What causes SPN 651?
Injector solenoid circuit open or shorted; Damaged harness under the valve cover; Worn or sticking injector; ECM driver fault.