# Service bulletin 20\-NA\-203

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: 11005341
- Published by NHTSA: 2024\-07\-30
- Manufacturer's number: 20\-NA\-203
- Manufacturer's date: 2024\-07\-17
- NHTSA component: ENGINE

## NHTSA's summary

This informational bulletin explains how the regen works for the DEF system and how it works at different levels.

## The document

- [NHTSA's copy of the document (PDF)](https://static.nhtsa.gov/odi/tsbs/2024/MC-11005341-0001.pdf)
- [If that address does not open, try this one](https://static.nhtsa.gov/odi/tsbs/2024/MC-11005341-9999.pdf)

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

## Components

Engine

## Vehicles listed

- 2019 CHEVROLET 6500
- 2018 CHEVROLET SILVERADO 1500
- 2018 to 2024 CHEVROLET SILVERADO 2500
- 2018 to 2024 CHEVROLET SILVERADO 3500
- 2019 to 2024 CHEVROLET SILVERADO 4500
- 2019 to 2021 CHEVROLET SILVERADO 5500
- 2023 to 2024 CHEVROLET SILVERADO 5500
- 2019 CHEVROLET SILVERADO 6500
- 2021 to 2023 CHEVROLET SILVERADO 6500
- 2025 CHEVROLET SILVERADO 6500
- 2018 CHEVROLET SILVERADO LT
- 2019 CHEVROLET duplicate SILVERADO 5500
- 2018 GMC SIERRA 1500
- 2018 to 2024 GMC SIERRA 2500
- 2018 to 2024 GMC SIERRA 3500
- 2018 GMC SIERRA DENALI

## Recalls for the same vehicles and component

- [2025225](/recalls/tc/2025225.md), 2025-04-24: Engine
- [25V274000](/recalls/nhtsa/25V274000.md), 2025-04-24: ENGINE AND ENGINE COOLING:ENGINE:HARD PARTS INTERNAL/MECHANICAL
- [21V346000](/recalls/nhtsa/21V346000.md), 2021-05-13: ENGINE AND ENGINE COOLING:ENGINE:ENGINE CONTROL MODULE \(ECU/ECM\):SOFTWARE
- [19V328000](/recalls/nhtsa/19V328000.md), 2019-04-25: ENGINE

## Other bulletins for the same vehicles and component

- [N262576260](/bulletins/11038468.md), 2026-10-15, Service campaign: ENGINE. General Motors has decided to conduct a Voluntary Emission Recall. Certain vehicles may have a condition that could cause a small exhaust leak at the catalytic converter inlet. Dealers are to replace the catalytic converter inlet clamp and to inspect the catalytic converter – replacing it if damage is observed. The repairs will be made at no charge to the customer.
- [N262548050](/bulletins/11031551.md), 2026-04-24, Service bulletin: ENGINE. This message is to inform dealers that Special Coverage N262548050 is being temporarily suspended for the models above. Involved vehicles will be temporarily removed from IVH. Dealers will be notified when repairs can be resumed. We apologize for any inconvenience this situation may cause.
- [N262548050](/bulletins/11031510.md), 2026-04-23, Service campaign: ENGINE. Certain vehicles, may have a condition that could cause the Catalytic Converter to fail. If this failure occurs, the Malfunction Indicator Light \(Check Engine Light\) will illuminate, and a diagnostic trouble code will set. Dealers are to replace the Catalytic Converter as necessary. The repairs will be made at no charge to the customer.
- [N252494003\-02](/bulletins/11027714.md), 2026-01-21, Service campaign: ENGINE. Certain vehicles listed above, may have a condition where the connecting rod and/or crankshaft engine components in these vehicles may have manufacturing defects that can lead to engine damage and engine failure. This special coverage covers if an engine failure occurs in the vehicle as a result of the condition described above for a period of 10 years or 150,000 miles \(240,000 km\), whichever occurs first, from the date the vehicle was originally placed in service, regardless of ownership. For vehicles covered by Vehicle Service Contracts, all eligible claims with repair orders on or after May 23, 2025, are covered by this special coverage and must be submitted using the labor operation codes provided with this bulletin. Claims with repair orders prior to May 23, 2025, must be submitted to the Service Contract provider. Vehicle owners or lessees who paid for repairs referenced in this Special Coverage \(“Customers”\) are eligible for reimbursement of their reasonable and customary expenses in accordance with the procedures specified below. The conditional right to reimbursement is provided by GM solely in the interest of customer satisfaction and is personal to Customers. Customers may not assign and GM does not consent to any assignment of any Customer’s right to submit reimbursement claims, or to receive reimbursement, or any other rights granted by this Special Coverage to any third party, including but not limited to service contract providers, and this Special Coverage is not intended to and does not confer any third party beneficiary, subrogation or contribution rights, or any other rights to reimbursement, against GM, whether in law, equity or otherwise, on any third parties. Dealers are to replace the engine. The repairs will be made at no charge to the customer.
- [25\-NA\-150](/bulletins/11026101.md), 2025-12-04, Service bulletin: ENGINE. This bulletin provides a procedure to check and replace the oil cooler seals before just replacing the oil cooler, for an oil leak.
- [00\-06\-01\-026R](/bulletins/11026017.md), 2025-12-03, Service bulletin: ENGINE. This service bulletin provides information on replacing the intake manifold when the engine is replaced after severe internal engine damage.
- [25\-NA\-339](/bulletins/11025492.md), 2025-11-12, Service bulletin: ENGINE. Under Field Actions N252494000, N252494001, the service procedure includes performing a PICO test on vehicle engines within the identified suspect VIN population. If the engine passes the PICO test, the engine oil will be changed from 0W20 to Mobil 1 Supercar 0W40 dexosR. From that point forward, the engine must use 0W40 dexosR oil products for all future oil change services.
- [23\-NA\-170](/bulletins/11024486.md), 2025-10-25, Service bulletin: ELECTRICAL SYSTEM; ENGINE. This bulletin advises the tech to inspect deeper into what may be to main cause of an engine failure.
- [23\-NA\-153](/bulletins/11024485.md), 2025-10-25, Service bulletin: ENGINE. The service bulletin advises the tech of a normal transmission shift condition and the delay in throttle response when the throttle plate is opened rapidly and advises the customer that it is normal for the delay.
- [25\-NA\-170](/bulletins/11024380.md), 2025-10-21, Service bulletin: VISIBILITY/WIPER; ENGINE. This service bulletin provides a repair procedure to correct a customer concern of Loss of Air Conditioning, Weak Cooling, and/or Warm Air Coming from Vents.

JSON: [/v1/bulletins/11005341](/v1/bulletins/11005341)

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