2007 Aspen 5.7 Limited 2WD 131k miles. Spark plugs new, then 1,900 road-trip. At the end of the trip after filling gas tank, it threw a CEL code P3449. Reset CEL and it threw a P3449 and a P3400. Reset the CEL, changed the oil (Mobil1 5w-20 and Mobil1 filter). Oil always maintained clean. Then swapped the #7 coil with the #3 coil and reset CEL. P3400 came back after 10 mi. run at 65 mph getting 20MPG. P3449 has not come back. Used Bosch 525x scan tool. All checked OK except P3400. Oil pressure at heat and idle was 10-12 PSI and 50 PSI at 1,500-2,000 RPM.

The vehicle runs great! No obvious issues. Asked Chrysler to disable the MDS and they said they can’t do it – against FCA (assume it means Fiat Chrysler America) policy.

Now, what to do? I no longer care about MDS and its gas savings. If I ignore the P3400 what could go wrong? If I drive it on road trips with the P3400 am I spraying fuel into cylinders that are not firing?

Thanks for all your input. If you know the answer or of technical documentation I can read (written by Chrysler engineers), much appreciated.

 

P3449 number 7 MDS solenoid p3400 mds rationality 1 Not spark plugs or coils. The MDS for turning off cylinders while driving 50 plus there is one or more with an issue they are under the intake manifold. I would change out all of them because there is likely trash in one or more of them

 

When MDS deactivated it runs on all 8 cyl.. It is like MDS deactivated. I had this issue. I fixed by replacing the MDS coils as they can plug up eventually.

 

Thanks Kevin for your time of feedback.

I had the Intake pulled and solenoids replaced February 2018 at 81k miles - just 50k miles ago.

What are the implications of ignoring this P3400 “Cylinder Deactivation System Bank 1” code – the long term bad?

I am approaching the point where I am questioning another $1,000+ into a maybe $6,000 vehicle.

 

Man. Need to change that text color. VERY difficult to read. Blends in too much.

 

It won't do anything to the engine really. It just won't run in MDS mode. Bad thing is it won't pass inspections with engine light on and worse, won't know if any other issues come about for tripping engine code if you are just ignoring the light that is already on. I actually have mine disabled with a Diablo Intune2 for the same reasons. Yeah, FCA may say it can't be done, but it can. Although I have replacement solinoids, their is just too much involved in replacing them and I can't afford paying someone else to do it. I found a used Intune2 for $150 from another member here and just turned it off. Reset codes after and no more engine light. Passes inspection. Runs fine for the most part (have other issues). Average 15 MPG. Mostly back country roads with a lot of turns. Can get higher on highway driving.

 

Thank you. Much appreciated. I now have my code reader / re-setter under the seat.

 

I agree, but my work around is to capture it as if to copy and then it is dark blue with white letters and easy to read.

 

it not my screen that has the issue all of my letters are white

 

Ah, I bet you are using "Dark Mode". Therefore the white letters are on black screen. With dark mode off, it's white letters on light grey screen so they blend in making it difficult to read.