P2509 Code 5.9 Cummins

ECM Power Input Signal Intermittent

This code means the ECM is not seeing a stable voltage coming from the vehicle electrical system.  This can result in all kinds of other issues due to the fact the 3rd Gen 5.9 Cummins trucks are heavily sensor dependent.  If the ECM doesn’t receive clean power from the vehicle, it can’t supply clean power to the sensors and the sensors will in turn provide bad data back to the ECM.

One of the main culprits is corrosion on battery terminals or the grounds.

Other possible causes

  • Dirty ECM Connector Pins
  • Bad battery or batteries
  • Failing Alternator


See my tuning in action…

High Altitude 12 Valve Tune Cold Start

An early version of my towing tune…