Toyota bulletin 23TC02a
What it saysRL: Due to certain programming in the brake ECU, under certain conditions, DTC U0100 is stored and cannot be cleared even though a technician attempts to do so. NHTSA’s full summary ↓
Toyota filed this with NHTSA as a service bulletin dated Jul 27, 2023, received Aug 28, 2023, about the engine. It names 1 model year (2023). 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 communicationRL: Due to certain programming in the brake ECU, under certain conditions, DTC U0100 is stored and cannot be cleared even though a technician attempts to do so. This condition does not affect the vehicle operation.
Trouble codes it names: U0100
Document filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| 23TC02a | Service bulletin | Jul 27, 2023 | 10241413 | not found |
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.
Doing the repair yourself, or pricing it before the shop does? Search the part by fitment on eBay Motors — the listing and the price are the seller’s.
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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 1 model year this bulletin names have filed 85 complaints with NHTSA since 2015. 13 of them name Engine — 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.
Drove car at reasonable low speeds (30-40mph) parked vehicle and noticed smell of something burning and light smoke. Opened hood and car was on fire. No mods, completely stock, low mileage. All services up to date. No reasonable explanation for sudden fire
2023 Toyota Corolla · Engine · filed with NHTSA Nov 30, 2025 · ODI 11702094
The contact owns a 2023 Toyota GR Corolla. The contact stated while driving at an undisclosed speed and attempting to slow the vehicle during a rainstorm, the brake pedal required excessive effort to depress while slowing the vehicle.
2023 Toyota Corolla · Service Brakes · filed with NHTSA Aug 20, 2024 · ODI 11609689
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 engine
Source: same model, same component group30 other manufacturer communications filed against the Toyota Corolla under the same component group (engine), newest first. The eight newest are listed; the rest are on the Toyota list.
| Number | Kind | Dated | NHTSA’s summary |
|---|---|---|---|
| T-SB-0110-20 OBSOLETE | Service bulletin | Aug 20, 2026 | OBSOLETE NOTICE August 20, 2026: This bulletin is now obsolete. Please see T-SB-0051-26. |
| 24TE04 | Warranty extension | Aug 11, 2026 | This Customer Support Program provides coverage as it applies to Flow Shut-off Valve Coolant Leak on Certain 2019-2021 Avalon & Avalon HV, 2… |
| T-SB-0104-21 OBSOLETE | Service bulletin | Feb 27, 2026 | OBSOLETE NOTICE February 27, 2026: This bulletin is no longer applicable and is now obsolete. |
| 22TC07 | Other | Nov 17, 2025 | Owner Renotification Letter Due to certain programing in the engine ECU, under certain conditions, the vehicle may stall at low speeds when… |
| T-SB-0088-23 OBSOLETE | Service bulletin | Aug 19, 2025 | OBSOLETE NOTICE August 19, 2025: This bulletin is now obsolete. Please see T-SB-0059-25. |
| T-SB-0059-25 | Service bulletin | Aug 15, 2025 | Some 2020 – 2025 model year Corolla vehicles may exhibit a vibration or rattle noise from the right-hand engine mounting insulator sub-assem… |
| T-SB-0112-24 REV2 | Service bulletin | Jun 19, 2025 | Some 2018 – 2021 model year Toyota vehicles equipped with an A25A-FKS, A25A-FXS, or M20A-FKS engine may exhibit a condition in which an “Eng… |
| T-TT-0784-25 REV1 | Service bulletin | Jun 17, 2025 | Some ECUs can set a DTC that is common with other ECUs. This can lead to accidental use of the wrong repair manual when diagnosing these typ… |
Quote the number at the service desk. It is what the dealer’s system is keyed on.
Every manufacturer communication NHTSA holds for Toyota, by the number printed on the letter.
Common questions
Source: NHTSA, 49 CFR 579.5Is Toyota 23TC02a 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 23TC02a 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. Every Toyota warranty extension on file lists the ones Toyota has filed.
Which vehicles does 23TC02a cover?
The manufacturer filed it against 1 model year: 2023 Toyota Corolla. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.