Code U1421

[salerno]

Started my truck last night 2016 Ram 2500 4x4 regular cab 8ft bed Diesel and got this code U1421. The truck ran fine no issues. I cleared the code and as of now still has not come back but was wondering if anyone has had this problem with 2016 trucks and what was their outcome? *Should I bring it to the dealer? Only have 6000 miles on it. Any help would be great. Thanks*

 

[Bob4x4]

The Body Control Module (BCM) monitors the time the ignition is in the off or accessory position between key cycles and then broadcasts the signal called Ignition Off Time (IOT) via the CANC Bus. The Powertrain Control Module (PCM) saves the value from a previous key cycle into powerdown flash and if certain ‘When Monitored’ conditions are met compares to the current value. If the ‘Set Conditions’ are met, then a fault U1421 is set indicating the timer is stuck. If this fault becomes active the PCM will light the MIL light immediately. If the MIL is set and the fault goes stored the PCM turns off the MIL after 3 consecutive drive cycles.

 

[Bob4x4]

When Monitored:
This diagnostic runs once with the ignition on provided there is a minimum 10°C (18°F) coolant temperature drop between previous ignition off and next key on; and power-down coolant temperature is greater than or equal to 76.6°C (169.88°F).

Set Condition:
If the difference between two Ignition Off Times (IOT) sent from the BCM to the PCM during two separate diagnostic decisions is less than 3 minutes for 5 consecutive decisions this fault will set.

 

[Bob4x4]

There is a tsb,18-037-16a that flashes the pcm and list your dtc as one of the issues that it is designed to address.
I would not clear codes and then decide weather or not to take it to a dealer for inspection.It just makes the techs job harder.

 

[salerno]

Some people have had their pcm's flashed only to have the same issue come back a few weeks later. There has to be a underlining issue rather then just a reflash of the pcm. When it comes back on, which Iam sure it will I will head to the dealership and let them try to fix it. Thanks for your advice.*