DEF issues - Please help

[montaz3]

I'm new to the board and will apologize now because this may have been answered somewhere already. I have a 2018 2500 Cummins with DEF problems.

It started out with the P203B-REDUCTANT LEVEL SENSOR 1 CIRCUIT PERFORMANCE code. Went through the harness and looked like the Diesel Exhaust Fluid Module was bad. Replaced. The DEF gauge still showing empty.

I cleared the codes and the DEF gauge went to full then 20 seconds later back to empty.

I took the truck for a test drive and while driving, all the DEF warnings went away, but gauge still showing empty.

I am now in limp mode. I am also still showing same code with the addition of P203C-(DIESEL EXHAUST FLUID) REDUCTANT LEVEL SENSOR CIRCUIT LOW.

I have now replaced the UREA PUMP/LEVEL UNIT and still have the same issue.

The DEF gauge shows it is empty, but I know there is DEF in the tank. Using a OBDLink M+ is see there is about 1/10th of a tank.

I am now getting U11C1-REDUCTANT CONTROL MODULE RECEIVED IMPLAUSIBLE DATA FROM ECM/PCM as well.

Any ideas?

 

[Brakoske]

Just curious have you found what the problem was?
Thanks

 

[montaz3]

I replaced the DEF module and pump and had it reprogrammed by the dealership. I think the module would have fixed the problem, but I did not know it had to be programmed prior to replacing the pump.

 

[Fuel35 67]

That’s how they get ya after the warranty is gone…….needs to be flashed. I’m starting to think these trucks should be stealth deleted.

 

[SF_bay]

Diesel engines idle issue: While i was looking over my owners manual on my 2022 2500 Longhorn some time ago I believe I read that there is an issue about not turning off the engine after a long drive, that its best to let engine idle a little to let the oil curculate to remove the heat. And this feature can only be done at the dealer, now for the life of me I can't find where I saw this in my manual. Is any one aware of this feature and is it in the manual. Thanks

 

[crash68]

Diesel engines idle issue: While i was looking over my owners manual on my 2022 2500 Longhorn some time ago I believe I read that there is an issue about not turning off the engine after a long drive, that its best to let engine idle a little to let the oil curculate to remove the heat. And this feature can only be done at the dealer, now for the life of me I can't find where I saw this in my manual. Is any one aware of this feature and is it in the manual. Thanks

Your probably thinking of the Engine Idle Shutdown found on the chassis cab trucks, according to this document it's not available on the pick up trucks.
There are several aftermarket options for turbo-timers, and yes it's a good idea to idle a diesel for a few minutes after working it hard before shut down.

 

[SF_bay]

Thank you for this info !!!

 

[GTyankee]

3 to 5 minutes idle time after a hard drive
like if you drive for an hour on the highway & pull a gas station or rest stop, let it idle a bit.

But if you leave the highway & then drive 4 city blocks to your house, the idle time is not needed, because during those 4 blocks, your RPM is fairly low