2019 gen 2 802a Check engine light for mandatory lamp failure

hey guys got a check engine light. Says code U0401, I ha e forscan set to no DRl, just running lights. All lamps work, the lights also come one when I auto start and if I move the switch to parking lights only. They are also on when the headlights are on.

Simply not on during the day when only the running lights (headlight surrounds, and parking lights and marker lights) should be on.

Any thoughts where to look? Currently on a road trip out at Glamis dunes in CA.

Really, nuthin?

a quick google search shows this code as invalid data received from pcm...

Yeah, saw that, but gives me no where to even start.

Might look into forscan when I get home.

Undo the FORSCAN mod and clear the code while in FORSCAN. Monitor for reoccurrence for a while. If the code does come back your stealership visit will be that much less dramatic.

Yep most likely the mods you made on forscan, revert back and see if it happens. Maybe you entered the wrong value somewhere?

It was fine for months, just happened randomly

BDF said:

It was fine for months, just happened randomly

Click to expand...

I'm curious as to why you think any of your DRL Forscan mods would have caused the CEL, then, if it's been working fine for months...