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12K views 10 replies 9 participants last post by  ekalb89  
#1 ·
Alright, I'm back again but with a new code this time. I own a 2018 RAM1500 EcoDiesel and this time I have a P0420 that the engine threw this afternoon after I drove after a while. The code read "Catalyst System Efficiency Below Threshold." The truck runs great. I see no difference in MPG, and performance is great! I just want to know if anyone else experience this code and what was done in order to remove it. I want to try everything before going to dealer and having them fix it. Everyone keeps recommending a catalytic converter cleaner but how do I know which one will do the job? Any brand recommendations? Any advice is recommended!!

Also, is it safe for me to continue driving the truck with this code on?
Thanks in advance!
 
#6 ·
Do not listen to anyone that recommended a converter cleaner LMAO.

Likely a clogged DEF injector. Remove the injector, inspect it, and steam clean it.
Will definitely try this and let you know if this worked. Truck is running great right now even with the code, so I am hoping it's just a faulty sensor or the injector like you stated.
 
#5 ·
He was actually in the dealer about a year ago because the truck had a P0299 code, I think. I can't remember what code it was, but I know it was the EGR cooler that needed to be replaced. Truck was in the dealer for about 1 week and I picked it up and it was running well once again. I did not experience any issue after that.
 
#4 ·
We regret to see that you're having these concerns with your truck. If you do decide to have this looked at by your dealer, let us know. We're available via direct message and can help with this process.

Callie
Ram Cares
 
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