I have a 2009 as well and my MDS works periodically at best. I kept getting these random P303 codes, they would come on and stay for a couple days then go off. I did any the normal things to fix this (new plugs, coil pack swap, o2 sensor). I started noticing that every time the check engine light came on I had a bad light bulb somewhere on my truck. After months of messing with this check engine light I noticed my puddle lamp in my drivers mirror was not working all the time. I changed the puddle lamp and my check engine light has never came back.

I know whats this have to do with MDS, but I recently took the truck on vacation and I got 17 MPG on the highway with my cruise set at 80MPH. I bought this truck new and I haven't got 17MPG in years. I think something with the P303 code and the computer would not let my truck use MDS.

 

P0303 is a misfire code. Misfire codes are commonly associated with a failed or lazy cam phaser. If I operate the truck with MDS active (which I don't), I can be assured of a misfire code popping up about every week or so. When I operate the truck in ERS (normal ops as of late), there is no issue with misfire codes.

 

The water pump was leaking so I took it in to get it fixed and I told the service guy about the random codes. Since I had the lifetime warranty he changed the sensor and put a new cam in it at the same time. I drove it for about 2 days and the same P303 code popped up again. That is when I noticed the puddle light and changed it. Its been about 4 months since I fixed the light and I haven't got one code since. My MPG has been much better in both city and highway driving. I think its safe to say these trucks have some electrical issues.

 

You can temporarily shut it off by hitting the "-" rocker on the column shift selector. The "+/-" on your instrument cluster will turn green when you do indicating MDS is off.

 

I have an 09 as well, and I can't really tell when MDS is on. As fare as I know, MDS is on all 1500 5.7s since 2006.

 

Hi all:
It has been a while but I seem to remember that my early 2009 with the Hemi had to have a software upgrade to get the ECO light to come on when the truck went into MDS mode. You might want to search the old threads for any info.
jimf5

 

I've been told several times that the Eco or Fuel Saver indicator is not the same as MDS activation. Its an indication you're driving economically. I'd prefer an MDS indicator, and I believe there's a way to put one in, but it requires a bit of work and wiring.

 

Isn't MDS activation just a couple solenoids, that re-direct oil flow to some of the lifters? Seems to me, just monitoring that circuit will tell you if it's active or not. Just wire a small lite in parallel with the circuit, and you should be good to go.