# Service bulletin 21\-NA\-238

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.

- Type: Service bulletin
- NHTSA id: 11020259
- Published by NHTSA: 2025\-07\-07
- Manufacturer's number: 21\-NA\-238
- Manufacturer's date: 2025\-05\-08
- NHTSA component: POWER TRAIN

## NHTSA's summary

This technical bulletin provides a procedure to inspect the front pump of the transmission for a possible leak.

## The document

- [NHTSA's copy of the document (PDF)](https://static.nhtsa.gov/odi/tsbs/2025/MC-11020259-0001.pdf)
- [If that address does not open, try this one](https://static.nhtsa.gov/odi/tsbs/2025/MC-11020259-9999.pdf)

The document is the manufacturer's. This site does not hold it.

## Components

Transmission and driveline

## Vehicles listed

- 2020 to 2025 CHEVROLET SILVERADO 2500
- 2020 to 2025 CHEVROLET SILVERADO 3500
- 2020 to 2025 GMC SIERRA 2500
- 2020 to 2025 GMC SIERRA 3500

## Recalls for the same vehicles and component

- [2026060](/recalls/tc/2026060.md), 2026-02-12: Powertrain
- [26V083000](/recalls/nhtsa/26V083000.md), 2026-02-12: POWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE:SOFTWARE; POWER TRAIN:AUTOMATIC TRANSMISSION:FLUID/LUBRICANT:VALVES/VALVE BODY
- [2024637](/recalls/tc/2024637.md), 2024-10-24: Powertrain
- [24V797000](/recalls/nhtsa/24V797000.md), 2024-10-24: POWER TRAIN:AUTOMATIC TRANSMISSION:FLUID/LUBRICANT:VALVES/VALVE BODY; POWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE:SOFTWARE
- [2020505](/recalls/tc/2020505.md), 2020-10-23: Powertrain
- [20V650000](/recalls/nhtsa/20V650000.md), 2020-10-22: POWER TRAIN:DRIVELINE:DRIVESHAFT

## Other bulletins for the same vehicles and component

- [N252502891\-01](/bulletins/11036308.md), 2026-08-20, Service campaign: POWER TRAIN. Certain vehicles may have a condition in which the internal differential nut was cross threaded or missing during assembly. Dealers will review the vehicles service history in IVH, and if necessary, replace the rear electric drive transmission module.
- [25\-NA\-080](/bulletins/11026044.md), 2025-12-03, Service bulletin: POWER TRAIN. This service bulletin provides a procedure to overhaul the control valve to replace a plate and worn down check ball to correct the customers concern of No Reverse, No Shift Past Third Gear \- DTC P2732 Set.
- [24\-NA\-262](/bulletins/11026024.md), 2025-12-03, Service bulletin: POWER TRAIN. This bulletin helps aid the tech in possible 10L100 transmission noise that may be normal or abnormal depending on the concern noted.
- [25\-NA\-108](/bulletins/11024499.md), 2025-10-27, Service bulletin: POWER TRAIN; ELECTRICAL SYSTEM. This bulletin provides a procedure to inspect and verify the drive shafts are over extending past the 5mm tolerance, causing the customers concern of a fluid leak under the vehicle.
- [25\-NA\-080](/bulletins/11024334.md), 2025-10-16, Service bulletin: POWER TRAIN. This service bulletin provides a procedure to overhaul the control valve to replace a plate and worn down check ball to correct the customers concern of No Reverse, No Shift Past Third Gear \- DTC P2732 Set.
- [N252517790](/bulletins/11024270.md), 2025-10-14, Service campaign: POWER TRAIN. Certain vehicles, equipped with 8L80 or 8L90 Transmissions, may have a condition in which the reaction carrier cracks. Dealers are to replace the reaction carrier.
- [N242454441 \-03](/bulletins/11024189.md), 2025-10-09, Service campaign: POWER TRAIN. Certain vehicles listed above, may have a condition where the transmission control valve has worn, resulting in a gradual loss of pressure within the valve. The effects can cause harsh shifting, setting a service engine soon message, reduced engine performance or P0747 diagnostic trouble code. Dealers are to install a new control valve body. The repairs will be made at no charge to the customer.
- [22\-NA\-182](/bulletins/11023369.md), 2025-09-27, Service bulletin: POWER TRAIN. This service bulletin advises the technician to check if the transmission cooler lines are twisted to correct customer concerns of Harsh Shift, Shudder, Surge, Stall, Transmission Overheating and/or High Transmission Fluid Temperature.
- [PIE0824A](/bulletins/11023057.md), 2025-09-10, Service bulletin: POWER TRAIN. This engineering information \(EI\) closure ends the need for gathering further information from field in regard to fluid leaking at the output seal and/or leaking at the front slip yoke \(welch plug leak\).
- [25\-NA\-014](/bulletins/11020428.md), 2025-07-08, Service bulletin: POWER TRAIN. This bulletin provides a procedure to overhaul the control valve to replace a plate and worn down check ball to correct the customers concern of No Reverse, No Shift Past Third Gear \- DTC P2732 Set.

JSON: [/v1/bulletins/11020259](/v1/bulletins/11020259)

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