Cummins Diesel Forum banner
Cancel
Create thread New Garage Forums

codes P0871 & P0734 please help

Jump to Latest
11K views 9 replies 5 participants last post by  Bkr1  
#1 ·
Just recently bought a 2007 cummins 6.7 megacab 3500 with exactly 170,028 miles on the clock. We are dealers and i bought the truck sight unseen other than pictures. Truck showed up yesterday. Batteries were dead and wouldn't take a charge. We put new batteries in this morning and truck fired right up. Went to take it for a spin and shifted fine till 4th and that was it. Went right into limp mode with the "4" next to "drive" on the dash. Cleared the codes, and same thing happened.
I have been searching the internet high and low and cant seem to get a definite answer or anyone who has had the combination of P0871 and P0734 together. I have seen from changing filters and making sure they seal good, to bad valve body, to new clutch packs and full rebuild.

I am not new to the cummins community, i have had several 2nd gens, a sterling 5500, and now this truck. Was planning to make it my daily driver and would really like to get this issue solved.

I would appreciate any input at all to give me an idea to start. Like i said i cant find anywhere on the internet the combination of the two fault codes together.

Also to further add the truck is fully delete.
 
#2 ·
Would assume that you've dropped the pan to check in there? The P0734 is a code specific to 4th gear (limp mode). The pressure code could be due to all the above mentioned. With those miles, you might get lucky with just being the valve body wear.
 
Save
Reply Quote Like Like
#3 ·
I have not dropped the pan yet. Wanted to see what some folks thought before I start ripping into it. Although my plan is to get it on the lift tomorrow and drop the pan to see what I find.
 
T
#4 ·
Likely a bad valve body (worn SSV bore) causing the P0871, but also likely the OD clutch was damaged thereby (causing the P0734). Probably needs an overhaul with a new VB assy. You could try just a valve body by itself first, and see if that takes care of it (while avoiding a trans pull). But if it still throws a P0734 (or P0735, P0729) after that, then the OD clutch is burned and it will need to come out.
 
#5 ·
Thanks for the info TransEngineer, i have seen you comment all over and was hoping you would see this and chime in. I appreciate the input and feel a little better having some idea what i could be getting into instead of a straight shot in the dark. at least it is some guidance in some direction.

Is there any specific brand valve bodies i should use or that are recommended or possibly any i should stay away from?

thanks again
 
T
#9 ·
The worn SSV bore is typically on a diesel (68RFE) trans, not on a gas engine trans. For a 6.4L I would first check the wiring. If the connectors all look OK visually, then I would do a "wire swap" to confirm whether the wire is the problem. I've described the wire swap routine in other posts; basically you swap the OD pressure switch wire (between trans and PCM) with one of the other pressure switch wires, at BOTH ENDS of the harness. If you then get the code for the "other" pressure switch, the wire is the problem. If you need more details let me know.
 
Cummins Diesel Forum
posts
9M
members
405K
Since
2005
A forum community dedicated to all things Cummins Diesel! Originally founded for owners and enthusiasts of Cummins powered Dodge pickups, the Cummins Forum has expanded to include ALL Cummins Engine applications! Come join the discussion about reviews, drivetrain swaps, turbos, modifications, classifieds, builds, troubleshooting, maintenance, and more!
Full Forum Listing
Explore Our Forums
03-07 Powertrain 03-07 Performance Parts Discussion 2013-2018 General Discussion 98.5-02 Powertrain 98.5-02 Performance Parts Discussion