Injector Metering Rail #2 Pressure - Current Above Normal or Grounded Circuit
What does JD-SPN660-FMI6 mean?
The JD-SPN660-FMI6 (John Deere PowerTech) diesel fault code means: Injector Metering Rail #2 Pressure - Current Above Normal or Grounded Circuit. This is a moderate severity code.
Common Symptoms
- Low power / derate under load
- Hard start or no-start after key-off heat soak
- Fuel knock at idle, particularly on cold start
Probable Causes (Ranked by Likelihood)
- Valve-cover injector harness broken at pass-through (classic PowerTech issue) Very Likely
- Sticking injector with carbon on control valve Likely
- Low rail pressure from HPFP wear or suction restriction Possible
- Water in fuel contaminating HPFP Possible
Step-by-Step Diagnostic Procedure
Inspect / swap cylinder injectors using Service ADVISOR cylinder-cutout test.
Measure actual vs. desired rail pressure at full load and on crank.
Drain primary water separator and recheck fuel filter service interval.
Check injector harness through the valve cover -- broken wire is a known failure.
Frequently Asked Questions
What is John Deere fault code SPN 660 FMI 6?
On John Deere PowerTech engines, SPN 660 FMI 6 means: Injector Metering Rail #2 Pressure - Current Above Normal or Grounded Circuit. Moderate code -- diagnose soon; continued operation may increase repair scope.
Can I keep using my John Deere tractor with SPN 660 FMI 6?
Moderate fault -- you can usually keep working but expect derate if aftertreatment-related. Diagnose with John Deere Service ADVISOR via an EDL v3 / CF3 interface.
How much does it cost to fix John Deere SPN 660 FMI 6?
Repair cost range: $250-$950 injector or rail sensor, $1,200-$3,800 HPFP. Dealer labor on large tractors runs $180-$240/hr in 2026.