2016 Ram 2500 - P208E Reductant Injector Stuck Closed - DEF system failing

Question

I'm getting a P208E code on my 2016 Ram. It started with a 'Service DEF System' message and now I've got the countdown saying it's going to limit me to 5 MPH in 40 miles. The tank is full of fresh DEF from a busy truck stop so I don't think it's bad fluid.

I can hear the pump priming when I key on, but I'm not seeing any consumption. I've crawled under there and checked the wiring to the injector and it looks okay, no obvious breaks or mice chewing on things. I really need to get this cleared so I can get back to work without the truck dying on me.

InternationalIan · Accepted Answer

✅ Confirmed fix: The reductant dosage valve (DEF injector) was internally seized. Even though it looked clean on the outside, it wasn't opening when pulsed by the PCM. Replaced the injector with a new Mopar unit and performed a 'DEF Reductant System Verification' test using a scan tool to reset the derate timers. The codes cleared and the truck successfully completed a stationary regen afterward.

NightShiftNate · Answer

Check your SCR catalyst efficiency while you're at it. Sometimes if the injector is stuck, it's actually crystallized DEF blocking the port into the decomposition pipe. You can try removing the injector and putting it in a bucket of hot distilled water to see if the crystals dissolve. If the nozzle is physically blocked by white crust, that's your starting point.

2016 Ram 2500 - P208E Reductant Injector Stuck Closed - DEF system failing

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