2021 ram service def system

[Morgan2021]

Question got a service def system on my 2021 ram went into count down mode took it to the dealer they plugged it in it had a knock sensor on bank 1 made an appointment for this fri driving it back home message went away and there is nothing in the stored messages and no check engine lite

 

[KneeDeep]

One thing I see on Mack trucks from time to time with that message is that the float level gauge in the def tank gets stuck and the tank could be empty even though the gauge shows it has fluid. I am not saying that is your problem, but it is easy enough to add def fluid if it has been awhile. I have not had that message on my 18 with 117,xxx miles yet or my 22 (knock on wood). I do not know if Rams could experience the same issue, but it’s an easy test.

 

[AH64ID]

Question got a service def system on my 2021 ram went into count down mode took it to the dealer they plugged it in it had a knock sensor on bank 1 made an appointment for this fri driving it back home message went away and there is nothing in the stored messages and no check engine lite

I presume you mean NOx sensor?

One thing I see on Mack trucks from time to time with that message is that the float level gauge in the def tank gets stuck and the tank could be empty even though the gauge shows it has fluid. I am not saying that is your problem, but it is easy enough to add def fluid if it has been awhile. I have not had that message on my 18 with 117,xxx miles yet or my 22 (knock on wood). I do not know if Rams could experience the same issue, but it’s an easy test.

The DEF tanks don’t use a float gauge like the fuel tank does. It’s an ultrasonic level sensor.

 

[Brutal_HO]

I presume you mean NOx sensor?



The DEF tanks don’t use a float gauge like the fuel tank does. It’s a capacitance style level sensor.

Thought it was an ultrasonic sensor.

 

[AH64ID]

Thought it was an ultrasonic sensor.

Correct, had the wrong term in my mind last night.

https://static.nhtsa.gov/odi/tsbs/2021/MC-10194039-9999.pdf