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2004 Dodge Ram 3500 P2149 Code: Diagnosis and Fix for Rough Idle and Injector Circuit Issues

Model: 2004 Dodge Ram 3500 Fault Code: P2149 Posted: 2014-05-03 11:27

I own a 2004 Dodge Ram 3500 with a 5.9L Cummins engine. Yesterday, while driving, the vehicle began running sluggishly and idling roughly. A diagnostic scan revealed code P2149. I'm seeking help to understand what this means and how to resolve it. The truck is stock—no modifications, chips, or magnets—and no other error codes are present. Everything else appears to be functioning normally. Can anyone provide insight into the likely cause of this issue? Specifically, is it related to wiring, injectors, or a fault in the power circuit for cylinders 4, 5, and 6?

Related fault codes

P2149

Comments (7)

Anonymous 2014-05-03 11:54

1) Which engine model? (e.g., 5.9L Cummins) 2) Are there any other diagnostic trouble codes? 3) Is the vehicle stock with no modifications like ECU chips, magnets, or performance tuning? 4) Are all systems operating normally—no warning lights or unusual behavior? For a 5.9L Cummins, P2149 typically indicates a wiring issue affecting cylinders 4, 5, and 6. The Powertrain Control Module (PCM) is not detecting proper voltage on the driver circuit. Please answer these questions so we can narrow down the cause. Also, do you have access to an OBD-II scanner or a digital multimeter (DVOM)?

Anonymous 2014-05-03 11:56

5.9L Cummins engine. No other diagnostic codes are present.

Anonymous 2014-05-03 12:01

Reread my post—my original message was edited after your reply to clarify the details.

Anonymous 2014-05-03 12:56

5.9L Cummins engine, stock configuration. No modifications or aftermarket parts. All systems are functioning normally with no other issues reported.

Anonymous 2014-05-03 14:28

Thank you for the detailed questions—this helps a lot. For cylinders 4, 5, and 6 (all powered by a shared circuit from the PCM), check the injector connectors at the cylinder head where they pass through the intake manifold cover. Ensure the connector is fully seated, free of corrosion, and not pinched or damaged. Specifically: the tan/pink wire carries voltage from the PCM; the other wire is the ground (driven by the PCM). Both wires should show proper voltage when the engine is off (KOEO)—do you observe this? If not, that points to a wiring fault or poor connection.

Anonymous 2014-05-04 12:45

There is no voltage detected on the power lines going to injectors 4, 5, and 6. Every 45 to 60 seconds, the system briefly sends a pulse of voltage to the injectors for a split second before returning to zero—this intermittent behavior suggests a faulty circuit or failing injector.

Anonymous 2014-05-04 16:05

In summary: This issue is likely caused by either a defective fuel injector or a wiring fault affecting cylinders 4, 5, and 6. The PCM shuts down the group to prevent misfires. Try unplugging each injector connector one at a time—start with the center set (cylinders 3–4), then move to the outer set (cylinders 5–6). Observe if the P2149 code clears or if engine behavior improves. This helps isolate which injector may be faulty. You can also perform an ohm test on the injectors—specification is typically greater than 0 ohms but less than 1 ohm (some sources suggest over 0.7 ohms, though this is more academic).