What Causes the P0871 Code?
As the leaders in engineering and manufacturing upgraded Dodge/Chrysler RFE/TE/RLE transmissions and parts, this is one of the most common questions we’re asked. The P0871 code is a rationality code indicating that the overdrive fluid pressure switch inside the solenoid pack was turned on at an inappropriate time.
This code is most common in the 68RFE, 66RFE and 65RFE but will also present in the TE and RLE series transmissions as well. When fluid pressure turns the pressure switch on in a gear the computer does not utilize the overdrive clutches for, the P0871 code will be indexed by the TCM.
A common mistake is diagnosing this problem as a solenoid pack issue because the code is spawned by i formation detected in the solenoid pack. Many people who get this code will change their solenoid pack believing it’s the problem. Generally speaking, the solenoid pack is not the cause of the code. The only way a solenoid pack can cause this code is if it fails in a way where the OD pressure switch feeds continuity/measurable resistance back to the TCM at an inappropriate time, a very unlikely failure.
So what causes the code? Nearly 100% of codes are caused by bore wear around the solenoid switch valve end plugs of the valve body. These are the 3 “cups” at the end of the solenoid switch valve complex, sometimes called shuttle valves. They move around very frequently, changing position every single shift. As a result, they wear out quickly and consistently.
Once they wear out to the point that oil can exit and enter adjacent circuits at inappropriate times, the transmission will attempt to apply inactive clutches at incorrect times, creating excess heat, poor shift quality, unpredictable shifts and, in many cases, the infamous P0871 code.
Additionally, this code is usually the last warning sign you will see before the overdrive clutches fail, requiring a transmission rebuild. This makes it important that you resolve this code the moment you see it to avoid a much more expensive failure.
How Do We Fix the P0871 Code?
As we now know, this code is strictly a valve body code. If there is evidence of clutch damage such as P0734/P0735/P0729/P0933 codes, a complete rebuild or replacement is necessary. If these codes are not present, a valve body replacement is likely all that would be required.
Next Gen Drivetrain RFE valve bodies are guaranteed to permanently resolve this code for life. We have designed several parts specifically to resolve the P0871 code and ensure that it cannot possibly return. Mainly, we physically machine the solenoid switch valve bore out to a larger diameter.
This restores bore integrity similar to boring and honing engine piston bores during an engine rebuild. Secondarily, we install a physically oversized, billet steel solenoid switch valve assembly with anti-seizure spring in every single RFE valve body. This not only returns the bore to perfect, better than new condition, it prevents the bore wear from developing again by using smooth-bore steel valves that do not abrasively damage the bore over time the way the feeble riveted factory valve does with its absurd “cleaning land” design.
Unfortunately, our extremely popular valve body DIY kit cannot fix this problem unless you install a physically larger solenoid switch valve with it because the solution for this problem is the machine work associated with a complete valve body. To permanently resolve this problem, our upgraded valve body is required. Still have questions? Call in and speak to a friendly expert today!
