[Jelease]

2018 Ram, I just replaced bank 1 NOX sensor yesterday with a aftermarket sensor and today drove approximately 25 miles and I get the P20EE code any suggestions thank you

 

[josiahg52]

Which NOx sensor did you replace? There are two. Suspect the source of your new NOx sensor, the wrong one was replaced, wiring to one or both sensors is damaged, or the SCR is actually bad.

 

[Jelease]

I replaced the upstream nox sensor . Is there a way to know if the SCR is actually bad? Thanks for the reply

 

[josiahg52]

I would've changed the downstream sensor. The only way to know for sure is to run the test plan for P20EE. SCRs very rarely fail outright and not by themselves except after many hundreds of thousands of miles. There is usually another factor at play that fouls the catalyst causing the inefficiency or causing the damage.

 

[Jelease]

Do you think I should replace that one also before going to the dealer? Don't want to spend all that money if I don't have to

 

[josiahg52]

If you take it to a dealer, unless you have a good relationship with a service advisor or the service manager, they will replace them as a matter of course and probably want you to approve replacement of the SCR. You could just use them for diagnostic use only and pay the one or two hours of labor for them to provide a repair plan and then do what they say. There could also be an issue with the DEF system causing this.