Cummins P2509 Engine Code

When you scan your Dodge/Ram Cummins engine and receive a P2509 diagnostic code, it will read ‘ECM/PCM Power Input Signal Intermittent Code’.

P2509 appears on Cummins engines when there is an electronic signal being sent to the ECM/PCM that is faulty or intermittent. Electronic signals are measured within parameters, and when the signal falls outside of the parameter range, the Power Input Signal Intermittent Code P2509 is thrown.

A Cummins P2509 engine code is a battery related issue. Either your battery is weak and running low voltages, something is draining your batter faster than it can charge, or there is a poor electrical connection. While all signs point to the battery, this trouble code can actually be caused by a number of issues, and replacing the battery isn’t always the answer.

Causes of a P2509 Fault Code – Cummins

Most Cummins diesel engines have a dual-battery setup. One battery is located on the driver side, and one on the passenger side within the engine bay. For most Cummins owners, P2509 is an issue with the driver-side battery. The majority of owners report that changing the battery solves the problem.

However, replacing the battery isn’t always the answer. This fault code can also be caused by:

• Driver side battery failure
• Bad battery connection (check connector cables)
• Bad alternator (over or undercharging batteries)
• Corroded battery cables
• Leaking batteries

If you are getting this fault code and have checked your battery connection, cables, and voltage, your issue could be your alternator. A weak alternator can cause your Cummins to not be able to start or continue running. Test your alternator and replace this if you don’t have any battery issues.

Cummins P2509 Fault Code Symptoms

The obvious symptom is the code itself, however, some additional symptoms may appear:

• Check engine light with P2509 code
• Hard start, no start (will usually still crank)
• Rough idling after engine start
• Battery voltage indicator is below 11 volts
• Engine shutoff while driving (if battery is being drained faster than charged)
• P2502 and P2503 codes

P2502 and P2503 Codes

These codes are known to appear alongside the P2509 code and will read ‘Charging System Voltage Low’. When you receive these codes all together, you might need to have your PCM reprogrammed.

Dodge/Ram released a Technical Service Bulletin (TSB) with number 18-001-07. Pre-2006 Cummins trucks had a common issue relating to a “check gauges” light combined with these three engine codes. A PCM programming malfunction is the result of this and can be fixed by taking your truck to a Dodge dealer and having them reprogram the PCM.