I have a real early '09 build. No light. Not worried about it. Don't need it. Just one more thing to distract your driving. I try to watch the road. Not some light that really doesn't do anything for me.

 

I turned off my fuel saver light. I don't care when it's in 4 cyl mode. I see no real difference in gas mileage, although logic tells me it should be double.

 

I took my truck in last week for a couple recalls. 1. Exhaust manifold bolts 2. A/C Actuator in dash 3. Seat covers, and one other one I think was a FLASH because my truck never had the MDS "Fuel Saver" light now it does so there is a flash for it.

 

Fuel save works differently depending when your 2009 Dodge vehicle equipped with 5.7L engine was built. If you have a vehicle that was built before December of 2008, maybe even later, then your fuel saver light will show only when driving around 30 to 45 mph. If you look at the serial number on the engine bar code (it will start with a T), you should be able to pick out the engine build date, which is based on the Julian calender, starts with year, then the date. So lets say you see something like 8249, that means your engine was built 9/5/2008. If you have an engine build date of 9XXX, and you do not get fuel saver light while going 55 MPH down the highway with cruise control active, then you have an issue with your vehicle.
Find some empty road somewhere, and start out at 30mph, set speed control, and watch fuel saver light, then go up a few miles per hour at a time.

You are really getting worried about nothing. Dodge added the fuel saver light because GM had it, and customers wanted to know when their vehicles were in fuel saver mode. Your ability to turn this light on really depends on how you drive the vehicle. If you drive like my wife, you will never see it, be on your second set of rotors, 3rd set of brake pads, and new tires with only 26K miles. Have I mentioned how much 275/60R20's cost?
One last thing, Fuel Saver Light is used to indicate when the vehicle is in a state that saves fuel. It is not solely based on whether the vehicle deactivates cylinders (MDS).

My 09 Laramie rambox gets around 17 miles per gallon when I drive, it gets about 14 when my wife drives. But then again, I anticipate red lights, I am slow to accelerate, I coast to lights, and if someone wants to get in front of me when I coast to a light, I let them. My wife accelerates hard to the stop lights, and stops hard when she gets there. Our kids drive the same way, probably because that's how they have seen her driving. I drive 64 MPH on the highway, and she drives 80.

 

She sounds like a real role model for the kids, LOL. My wife since we got this truck seems to be a bit more of a lead foot too. Here I went thru all the hassle of getting the Fuel Saver light and I am the only one that worries about it.

 

My truck didn't have it (Oct 08) build until I asked for it last month when my 2 year inspection ran out, now I have it and really like it! It is not distracting at all, very small fuel saver light same area as mileage , same color as all the other info, if you aren't distracted by the mileage number changing each mile it wont bother you at all!

 

Some people could care less if they have it or not. BUT. If the truck is equipped with the light it SHOULD work. And I will grind every dealership until I find one that knows what the f**k they are doing.
Nathan are you reading this??????????

 

This is very true, I have certainly noticed this and even when I turn off MDS using the flashpaq tuner, the light still comes on. This entire MDS mode is just plain annoying, I live on back country roads and wish I could set it to come on only above 55 mph for highway cruising. The constant in and out of MDS mode can't be good for it and will be disabled after the dealer visit after this recall is done.

 

just a quick note back to your not having headlight indicator light. I thought I had this same problem. realized auto lights are only on in darker conditions like dusk or night. The light is actually the foglight indicator and only on even in auto if you push for fog lights.

just my 2 cents since I thought i had same issue but did not

 

Called my dealership asking for specific updates that they may have done to make the software now notify fuel saver mode. They simply stated it like this. We plug it in, it says it needs a software update, we treat it like a windows upgrade. We click okay, and it does it's thing. We didn't even know it added the feature to your truck.