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Re: C9s - Diagnostic code query

SPN 515 - Eng's Desired Operating Speed

FMI 8 - Abnormal Frequency, Pulse Width, or Period


This indicates there is problem with the throttle signal going to the engine ECM


C9s - Diagnostic code query

I am periodically receiving the following Diagnostic Code on shutdown.

SPN 515

FMI 8.


Engines are 503HP c9s.  CSN00625 and CSN00630


Sometimes it is the Port engine, sometimes the Starboard.


I can't 100% replicate it but I *think* it shows up when I have had the RPM sync'd at some stage during the trip, and perhaps also when I have used low speed idle at some stage.


Any thoughts?  I can't find anything definitive online.


Thanks in advance.