P0872: How to Diagnose & Fix — Transmission Fluid Pressure Sensor/Switch 'C' Circuit Low
2 vehicles · 2 makes · $300-$4,800 repair
How to diagnose and fix P0872: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Chevrolet Silverado 2500HD · 2001–2019
Separate from the well-known torque converter shudder, the Allison 1000 in these trucks is documented for shift solenoid faults that drop the transmission into limp mode. The TCM sets P0700 - a generic 'transmission fault' pointer - accompanied by a specific code such as P0871 or P0872 (pressure switch E reading wrong for the commanded state of shift solenoid E, often caused by the solenoid or a sticking valve). When that code sets, the transmission falls to hydraulic default, the TCM inhibits torque converter clutch engagement, and the truck is left in a single gear, usually third, sometimes refusing to move at all until it is restarted. On a loaded 2500HD this strands the truck. Forum diagnosis repeatedly finds the cause outside the solenoid itself: low or burnt fluid, a loose battery ground, or a chafed harness behind the transmission.
Common Symptoms
- Transmission stuck in one gear (limp mode)
- Check engine light with P0700
- Harsh or no shifts
- Torque converter clutch will not lock up
- Truck will not move until restarted
- Service transmission message
How to Fix
Do not open the transmission on a P0700 alone - read the sub-code first. Check fluid level and condition, then inspect the internal wiring harness pass-through connector, the transmission harness where it routes behind the case, and the battery/chassis grounds, all documented causes of these codes. If the solenoid body is genuinely at fault, the internal control solenoid body and the internal harness are replaced with the pan down. Fluid and filter service on the Allison's real interval (much shorter for tow and plow duty) is the strongest prevention. No recall covers this.
Sources for this issue (5)
- Allison 1000 issues and limp mode - Chevy and GMC Duramax Diesel Forumforum
- Allison 5sp: Limp mode bad solenoid - DuramaxDiesels.comforum
- Allison Transmission P0700 Code Help - Chevy and GMC Duramax Diesel Forumforum
- Allison pressure switch codes - Transmission Digestarticle
- Allison 5sp: Codes set P0847 & P0872 - DuramaxDiesels.comforum
RAM 2500 · 2007–2024
The 68RFE 6-speed automatic behind the Cummins is prone to torque converter shudder and lockup failure. The factory converter's clutch material and heat control are marginal for the Cummins' torque, so the torque converter clutch (TCC) chatters, slips, or refuses to hold lockup, felt as a low-speed vibration like driving over rumble strips. The TCC regulator valve wears its bore in the valve body, making apply pressure erratic. The resulting heat contaminates the fluid and cascades into planetary and clutch-pack damage. Heat is the number-one killer, especially when towing; fluid temps regularly over 200°F accelerate failure.
Common Symptoms
- Shudder/vibration around 40-55 mph (converter lockup)
- Slipping or flaring on lockup
- High transmission temperatures when towing
- Harsh or delayed shifts
- Burnt-smelling ATF+4 fluid
- Check engine light with TCC codes
How to Fix
Replace the torque converter with a stronger billet/multi-disc unit (e.g., Sun Coast triple-disc or BD Diesel) rather than another stock converter. Rebuild or upgrade the valve body / TCC regulator valve (Sonnax) to restore correct apply pressure. Add an auxiliary transmission cooler and use the correct ATF+4 fluid, and consider a deep pan and improved fluid capacity for towing. Address early to avoid a full transmission rebuild.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- BD Diesel 1070220X ProForce enhanced-stall 68RFE torque converter
Restrict approval to manufacturer-cataloged 2007.5-2018 Ram 2500/3500 6.7L with 68RFE; verify early-2011 six- versus eight-bolt configuration and core terms. Do not extrapolate seller claims through 2024 without PI-curve/year confirmation.
- Genuine Mopar 68218058AC ATF+4 fluid
ATF+4/MS-9602 applications only; confirm container size, exact service quantity and current service information.
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Sources for this issue (3)
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P0872 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0872 mean?
P0872 stands for "Transmission Fluid Pressure Sensor/Switch 'C' Circuit Low." The transmission fluid pressure sensor/switch 'C' circuit voltage is below the expected range (too low / shorted to ground).
What are the most common causes of P0872?
The most common causes of P0872 are: Sensor signal shorted to ground, Faulty pressure sensor/switch C, Corroded/damaged connector, Internal TCM fault. The specific cause varies by vehicle.
How much does it cost to fix P0872?
Repair costs for P0872 range from $300 to $4,800, depending on the vehicle and root cause.
Which vehicles are affected by P0872?
Au7o has documented P0872 across 2 vehicle models from 2 manufacturers: Chevrolet, RAM.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.