Check engine light - "deactivation sensor"

[ChrisG]

2022 RAM 1500 5.7 Hemi 82K miles
Check engine light came on on the highway
Dealer ran the code and reported "cylinder #1 deactivation sensor". Said there was no way to diagnose it further without engine work. Engine runs and sounds normal and power is normal. ECO mode seems to still work OK.
Does this have to do with the ECO mode not shutting off cylinder #1 when under light load?
Thanks.

 

[markabby]

maybe a bad wire? ground or something?

just a guess.

 

[ChrisG]

maybe a bad wire? ground or something?

just a guess.

Thanks. It sure does seem like a wire disconnect or bad ground. I haven't dug around to look yet, but will.

 

[Ken226]

It is the MDS Solenoid, not a sensor. It opens to allow oil pressure to collapse the lifters when activating MDS mode, and shuts off the oil to reengage the lifter. You'll need to remove the fuel rail and intake manifold and the foam insulator to get at it.

#1 is the bottom right





Yours may be different as this is from a 2013-2015 manual, but i doubt it is significantly different.

 

[ChrisG]

Thanks so much, Ken. That's really helpful. - Chris