Have a wrangler thats showing a p0731 gear ratio error in 1st after swapping in 4.56 gears and 315/70R17 around 35". The dealer only has the option to change the tire size slightly. What are you guys doing to run gears and larger gears?

 

U need to correct the speedo using something like a aev procal or a super chips tuner and also correct the axle ratio the computer is set to.. my superchips has both options.
Welcome to the forum.

 

Thanks for the welcome, I joined awhile back just been lurking a while. I'll look into both of those tuners.

 

I just did a gear swap on our 2013 to 4.88 and as soon as I pulled it out of the garage it went into Limp mode and gave me the P0731 code.
I have had 4 JK's and never had this problem after regearing, so it looks like the 2013's have to have the ECM reprogrammed right away?
I usually reprogram anyway but if you didnt it wasnt a big deal and the speedo would just be off.

Did you get your jeep programmed and did it fix the problem? Has anybody else had this problem?

 

just went to 4.88 on my 13 JKUR. Used the Procal to change the ratio before I drove it and have not had a code. I was warned before the swap that it would go to limp mode right away if I didnt have the ratio changed.

 

Any dealer or shop worth their salt should know this issue on 2012+....especially with auto transmission.

I would be worried about a shop doing my gears who was not aware if this.

Also not knocking your gear choices, but 4.88s plus is a very high number for a 2013. Many shops are still recommending old school JK gears for newer power trains.

I think there is an epidemic of shops out there who fundamentally do not understand the difference between 2007-2011 vs 2012+ JKs. They have not taken the time to research or apparently have not work on many.

 

1. I did the gears myself so I am confident in the shop that did them.
2. This JK is running 37's and will be mainly used for Moab and I wanted it geared on the low side so 4.88's will be perfect.

 

Thanks, that is exactly the response I was looking for.

 

I agree with this... a lot of shops only stock 4.88's so when you ask what they recommend they say 4.88.

 

How did the DIY gear swap go? I may give it a shot.....