Chevrolet bulletin 21-NA-049
What it saysThis service bulletin provides a Diagnostic Aid for PicoScope Information and Setup for Transmission Related Concerns. NHTSA’s full summary ↓
Chevrolet filed this with NHTSA as a service bulletin dated Jan 14, 2025, received Aug 4, 2022, about the power train — 5 documents under this number. It names 6 model years (2020–2025). A service bulletin is not a safety recall: it is the manufacturer telling its dealers how to diagnose or repair a condition, and whether the work is paid for depends on the warranty in force. Quoting the number at a service desk can save a diagnosis.
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What the bulletin says
Source: NHTSA's summary of the manufacturer's communicationThis service bulletin provides a Diagnostic Aid for PicoScope Information and Setup for Transmission Related Concerns.
Documents filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| 21-NA-049 | Service bulletin | Jan 14, 2025 | 11013241 | PDF, 249 KB |
| 21-NA-049 | Service bulletin | Jan 31, 2024 | 10250273 | PDF, 128 KB |
| 21-NA-049 | Service bulletin | Nov 17, 2023 | 10245556 | PDF, 125 KB |
| 21-NA-049 | Service bulletin | Jun 6, 2023 | 10237936 | PDF, 137 KB |
| 21-NA-049 | Service bulletin | Jul 29, 2022 | 10217096 | PDF, 124 KB |
The summary is NHTSA’s abstract of the document, as filed under 49 CFR 579.5. One communication is usually filed as several documents — the bulletin, a dealer notice, an owner letter — and the number on any of them finds this page. A PDF link is shown only once NHTSA’s own server has been seen to serve that document; the rest are checked over the following nights. Quote the number at a service desk; it is what the dealer’s system is keyed on.
Model years it names
Source: as the manufacturer filed themA vehicle page’s bulletin list shows the newest few communications filed against that model year; the count there is every one.
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What owners reported
Source: NHTSA complaint databaseOwners of the 6 model years this bulletin names have filed 124 complaints with NHTSA since 2015. 46 of them name Power Train, Electrical System — the same broad component group this bulletin is filed under. NHTSA groups complaints coarsely, so that means the same area of the vehicle, not necessarily the same fault.
I bought this car from a dealer .that buys buy back cars from Gm .when i bought the car the dealer stated all service have been done . well i took to get oil changed and chevy told me they had no record of this service.the 2024 corvette gets a free oil and trans service from chevy.it has got to be done before 7500 miles .well the dealer…
2024 Chevrolet Corvette · Power Train · filed with NHTSA Jun 23, 2026
I cannot believe the Corvette does not show that the alternator does not show that the car is not charging. I have a thirty year old corvette that will show you when the alternator does not show the car has an under performing alternator. If you do not have it showing on the display it will not show you that the alternator is defective.
2021 Chevrolet Corvette · Electrical System · filed with NHTSA May 3, 2025
I replaced the battery in my C8 Corvette after three years of ownership. Upon removing the plastic cover from the frunk to access the battery, I discovered the two front strut mounts. To my dismay, I noticed excessive corrosion on both strut mounts, with the left side near an AC compressor line being considerably worse.
2020 Chevrolet Corvette · Power Train · filed with NHTSA Feb 20, 2025
A complaint is one owner’s account, not a defect finding, and a bulletin is not a recall. Nothing here says this bulletin was issued because of these complaints, or that the repair it describes fixed them. Complaint files on this site begin in 2015.
More bulletins about the power train
Source: same model, same component group48 other manufacturer communications filed against the Chevrolet Corvette under the same component group (power train), newest first. The eight newest are listed; the rest are on the Chevrolet list.
| Number | Kind | Dated | NHTSA’s summary |
|---|---|---|---|
| PIE0835 | Service bulletin | May 9, 2025 | This engineering information (EI) is requesting information from technicians to perform the check list provided and contact the engineers li… |
| 23-NA-156 | Service bulletin | Mar 28, 2025 | This service bulletin informs the technician on the running changes to the M1L, M1M and MLH automatic transmission. |
| PIP5966A | Service bulletin | Mar 2, 2025 | This Preliminary information communicates Diagnostic aids for a no start or DTC'S following a transmission replacement |
| 16-NA-019 | Service bulletin | Feb 12, 2025 | This informational buleltin provides information on Transmission Adaptive Functions and Correcting Low Mileage Harsh Shifts, Slips, or Flare… |
| 09-06-04-026Z | Service bulletin | Jan 9, 2025 | This bulletin provides information on identifying Non-GM Engine Calibrations for Gasoline Engines using the Tech 2 or GDS 2. |
| 24-NA-273 | Service bulletin | Jan 7, 2025 | This service bulletin provides a procedure to replace the Drive Motor Disconnect Clutch Actuator to correct a customer concern of a Malfunct… |
| PIP6026 | Service bulletin | Dec 4, 2024 | This Preliminary Information communication advises the technician on the need to provide additional information when creating a TAC case for… |
| 08-07-30-035I | Service bulletin | Nov 27, 2024 | This service bulletin provides information on the harmful effects of ethylene glycol in transmission fluid. |
Quote the number at the service desk. It is what the dealer’s system is keyed on.
Every manufacturer communication NHTSA holds for Chevrolet, by the number printed on the letter.
Common questions
Source: NHTSA, 49 CFR 579.5Is Chevrolet 21-NA-049 a recall?
No. A service bulletin is a manufacturer communication filed with NHTSA under 49 CFR 579.5; a safety recall carries an NHTSA campaign number (two digits, a letter, six digits) and a federal duty to repair for free. Check the vehicle’s recalls by VIN at nhtsa.gov/recalls, or on its page here.
Is the 21-NA-049 repair free?
Not automatically. A service bulletin describes how to diagnose or repair a condition; who pays depends on the warranty in force, any extension, and the dealer. Quoting the number can save a diagnosis either way.
Which vehicles does 21-NA-049 cover?
The manufacturer filed it against 6 model years: 2025 Chevrolet Corvette, 2024 Chevrolet Corvette, 2023 Chevrolet Corvette, 2022 Chevrolet Corvette, 2021 Chevrolet Corvette, 2020 Chevrolet Corvette. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.