I have a 2017 ED and it has the P203E and P204F codes. Even though the DEF fluid is at least 5 gallons, it used to register as empty. The count down to not starting started at 1500 miles. I've done all the suggestions including removing the tank and flushing it with hot, distilled water. All to no avail. In the last 200 miles, the same codes exist (erased multiple times) the DEF meter flipped to now reading pegged on full. I've read all the pertinent threads and was prepared to run a push button into the cab from the relay as found on this forum. My warning finally counted down to zero and turned to "Will Not Start, Fill DEF". I timed it to be at home and was getting the wiring out ready to do the jury-rig... and the truck keeps starting, but keeps showing the warning.
What's up with this?
BTW - I have a 2019 GDE Tune. It does not mention that it bypasses this, "Will not Start" warning, but so far I can still start it.
With my 2014 RAM Ecodiesel I have experienced the same problem:
Code P203E, DEF guage stock in certain position and eventually the warning came that after 400 miles the engine shuts down.
Root cause: DEF Level Sensor inside of tank failed due to crystallized DEF.
Prevention: use highest quality DEF (DEF blue, the expensive one)
Deler Proposal: Change DEF tank, because senor in integrated inside of the DEF tank. (The expenses in US up to $4K.)
My fix:
Parts needed:
1- Purchased small DC high pressure fluid pump motor from Amazon ($30)
2- Purchased spray nozzle (about
$20)
3- Pipe to to connec spray nozzle with the high pressure pump.
4- AC/DC transformer or a strong DC supply voltage or a 12 V car battery to Rum the pump.
5- 2 gallons of distilled water.
Fix procedure:
1- Under the vehicle find the DEF tank
2-On the rear of DEF tank where the DEF supply hose is connected (it has a green plastic connection locking mechanism) by pushing the plastic lock with fingers the hosr can be disconnected fron the tank.
3a- Use this opening utilizing the fluid pump by inserting the pipe into the DEF tank to suck out all residual DEF from the tank into a container for disposal. (Bring it later to a recycling station!).
3-B When DEF tank is empty, warm up the distilled water to a temperature about 75⁰C. (Make sure that the pipe you are using can handle this temperature).
This time use the pump not as water pump, but as high pressure pump by using the spray nozzle spraying the warm distilled water from the top carefully into the tank.
Important Considerations:
My spray nozzle was slightly larger diameter as the tank opening.
I was not able to insert the spray nozzle into the tank, but I sprayed fron the opening into the tank.
If you can find a smaller nozzle maybe the nozzle and the pipe can be inserted into the tank and the process could be more effective. But my procedure was enough to fix this problem as well. )
If you inserting the nozzle into the tank you should make sure that the nozzle is fastened securely on the pipe otherwise it can disconnect and fall into the tank. Secondly if you inserting the nozzle into the tank make sure that you do not damage the sensor. I am not sure about the exact location of the senor, but I reason that ultrasonic sensor is somewhere in the top of the DEF tank.)
After spraying the tank and hopefully cleaning the sensor from crystallized DEF residue.
4- Pump out all the distilled water out of the DEF tank. (Using the step 3A)
5- Connect the hose back to DEF tank make sure it clicks and locks.
6- Fill the tank with 3/4 of DEF capacity. (Check user manual for DEF tank capacity. (use high quality DEF, the expensive brand)
7- Add some DEF additives that avoids DEF crystallization.
Comment: I cannot guarantee that this procedure will fix your code P203E and fix the DEF guage and reset the count down counter, but it did fix these problems for my RAM 2014 Ecodiesel.
As a retired car engineer I would highly encourage RAM to assure for future models the DEF sensor can be easily replaced!
Further I think the RAM dealerships are scamming the customers by replacing the tank for $4000 and offering no other solution for this problem.