Service bulletin 0900321REVA

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

The communication, as NHTSA indexes it (as of 2026-10-19)
Type	Service bulletin
NHTSA id	10220988
Published by NHTSA	2022-09-26
Manufacturer's number	0900321REVA
Manufacturer's date	2021-03-30
NHTSA component	POWER TRAIN

NHTSA's summary

Transmission Oil Cooler Lines Not Fully Connected This bulletin involves inspecting the Transmission Oil Cooler (TOC) lines and reconnectingif necessary. Customers may experience a Malfunction Indicator Lamp (MIL) illumination. Upon further investigation the technician may find one or more ofthe following Diagnostic Trouble Codes (DTCs). P1D90-00 Incorrect Gear Ratio - Clutch 2 Defective. P1D91-00 Incorrect Gear Ratio - Clutch 3 Defective. P1D92-00 Incorrect Gear Ratio - Clutch 4 Defective. P1D93-00 Incorrect Gear Ratio - Clutch 5 Defective. P1D95-00 Tcm Clutch Failure Undetermined. P1B14-00 Park-By-Wire - Unintended Park Position. P1B13-00 Park-By-Wire - Unintended Out Of Park Position. P1D99-00 Incorrect Gear Ratio: Clutch B Or E Defective. P1D9A-00 Incorrect Gear Ratio: Clutch C Or D Defective. P1D95-00 Tcm Clutch Failure Undetermined. P07E4-00 Unable To Engage Park. P1DCD-00 Tcm Monitoring Processor Performance - Multiple Clutches Locked Up. P0735-00 Gear 5 Shift Incorrect Ratio. P0919-00 Gear Shift Position Control Error. Customers may also experience the following:Transmission fluid leaking under vehicle. The vehicle will not shift. Slow shifting between gears.

The document

The document is the manufacturer's. This site does not hold it. NHTSA files a document at one of these two addresses; we have not asked NHTSA which.

Components

Transmission and driveline

Trouble codes named

P0735, P07E4, P0919, P1B13, P1B14, P1D90, P1D91, P1D92, P1D93, P1D95, P1D99, P1D9A, P1DCD

Vehicles listed
RAM 1500	2021

Listing a model year does not mean every vehicle of it is concerned: the document says which.

Recalls for the same vehicles and component
23V265000	2023-04-13. POWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE (TCM/PCM/TECM)

A recall listed here may apply to some of the same vehicles. Only the manufacturer can say whether it applies to one vehicle.

Other bulletins for the same vehicles and component
S2621000004	2026-10-07. Service bulletin. The Customer May Complain About a Popping Noise, Grinding Noise, or an Intermittent No Reverse or Forward Transmission Engagement. The Tech May Find Damaged and/or Worn Transmission Output Shaft Splines (850RE Transmission Only)
21-056-26	2026-07-18. Service bulletin. Flash: Transmission Control Module (TCM) Updates Customers may comment on one or more of the following: SYMPTOM: ● Harsh or slipping feeling during upshifts (1st - 5th). ● Harsh or slipping feeling during kickdown events under throttle. ● Transmission fluid odor (burnt smell). ● During a 2 - 3 transmission upshift, the engine is hitting rev limit. ● Hesitation feel during a pedal tip in, while engine is warming up below 1 °C (30 °F) ambient temp. This bulletin involves reprogramming the TCM with the latest available software.
S2621000003 REV.A	2026-03-18. Service bulletin. The vehicle will exhibit a service transmission/check engine warning indicator for the following transmission models: 845RE, 8HP45, 850RE, 8HP50, 8HP70, 8HP75, 8HP75-PHEV, 8HP75-LCV, 8HP90, 8HP95. Transmissions may exhibit the following diagnostic codes: P07E4, P1DB2, P0716, P1B14, P0733, P1D90, P1DB7, P1B13.
S2621000003	2026-03-05. Service bulletin. Service transmission/check engine warning indicator for the 850RE, 8HP50, 8HP70, 8HP75, 8HP75-PHEV transmissions that have fault codes P07E4, P1DB2, P0716, P1B14, P0733, P1D90, P1DB7, P1B13.
03-008-25	2025-09-24. Service bulletin. Rear Axle Vibration Shudder Or Chatter Customers may experience the following: ● A chatter, shudder, or vibration from the rear axle during turns. NOTE: This may happen more as the vehicle ages, especially if the vehicle is used extensively for towing or hauling heavy loads. The cause of the concern may be due to degradation of the rear axle fluid. It is very important to follow the routine maintenance schedules on these vehicles when it comes to changing the rear axle fluid if the vehicle is used primarily for towing or hauling heavy loads. If you experience a vehicle with the above condition, please perform the proper maintenance procedures for the rear axle and replace the fluid first before replacing any hardware components. NOTE: This service bulletin is only applicable to vehicles that have no history of an axle fluid replacement. If the vehicle usage includes police, taxi, fleet, off-road or frequent trailer towing, regular axle fluid changes are required every 3 years or 30,000 miles (whichever comes first) per the Maintenance Schedule in the vehicle Owner's Manual. This bulletin involves changing the rear axle lube to possibly address a chatter, shudder or vibration.
9100627	2025-07-23. Service bulletin. To inform dealers about the 850RE valve body PN: R8348504A connector: the original 16-pin connector included six pins that were not used in this application. To simplify the design, the connector has been optimized and updated to a 10-pin configuration.
21-029-25 REV. A	2025-07-09. Service bulletin. 8HP75 D Clutch Repair Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must have at least 11,265 km (7,000 mi.) and exhibit/set one or more of the following Diagnostic Trouble Codes (DTCs): ● P0733-00 - Gear 3 Shift Incorrect Ratio. ● P1DA8-00 - Incorrect Gear Ratio Clutch A B or D Defective. ● P1D92-00 - Incorrect Gear Ratio - Clutch 4 Defective. Customers may also comment on the following: ● Vehicle enter limp home mode. This bulletin involves replacing the D clutch.
21-009-25 REV. C	2025-07-09. Service bulletin. 850RE D Clutch Repair Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must have at least 11,265 km (7,000 mi.) and exhibit/set one or more of the following Diagnostic Trouble Codes (DTCs): ● P0733-00 - Gear 3 Shift Incorrect Ratio. ● P1DA8-00 - Incorrect Gear Ratio Clutch A B or D Defective. ● P1D92-00 - Incorrect Gear Ratio - Clutch 4 Defective. Customers may also comment on one or more of the following: ● Transmission slips when shifting. ● Vehicle will not move in reverse. ● Vehicle will not shift higher than third gear This bulletin involves replacing the D clutch.
03-004-25	2025-05-19. Service bulletin. "Front Drive Unit Vibrates Customers may experience the following: ● Vibration in the front of the vehicle from the front drive unit This bulletin involves replacing the right front output shaft."
9100570	2025-05-19. Service bulletin. "Transmission Fluid Please note fluid color/condition/odor is NOT an indicator of transmission health and should not be used as the reason for unit replacement. Visible ""glitter"" or debris in the pan does not justify complete unit replacements."