Toyota bulletin T-TT-0784-25 REV1
What it saysSome ECUs can set a DTC that is common with other ECUs. NHTSA’s full summary ↓
Toyota filed this with NHTSA as a service bulletin dated Jun 17, 2025, received Jul 10, 2025, about the engine — 1 document under this number: T-TT-0784-25 Rev1. It names 49 model years (2017–2025). 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 communicationSome 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 type of DTCs.
Document filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| T-TT-0784-25 Rev1 | Service bulletin | Jun 17, 2025 | 11020664 |
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 themand 9 more on this site: 2022 Toyota RAV4 Prime, 2021 Toyota RAV4 Prime, 2024 Toyota Venza, 2023 Toyota Venza, 2022 Toyota Venza, 2021 Toyota Venza, 2025 Toyota bZ4X, 2024 Toyota bZ4X, 2023 Toyota bZ4X.
A 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 49 model years this bulletin names have filed 4,275 complaints with NHTSA since 2015. 649 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.
On the 2019 Toyota Camry, the 30 owners who gave an odometer reading for Engine reported it at a median of 31,000 miles. That figure is one model year’s, not the whole range this bulletin covers — medians from different model years are not averaged.
Excessive oil consumption - new vehicle newly purchased 2019 Toyota Avalon xle (6 cyl) has excessive oil consumption. Required addition of 2 quarts of oil at 2,000 miles. No leaks evident under car. At 3,100 "low oil" light came on, but could not check because dealer taped dipstick to prevent me from checking. Dealer tearing apart engine
2019 Toyota Avalon · Engine · filed with NHTSA Aug 23, 2019 · ODI 11246041
Coolant is leaking into the catalytic converter. This seems to be a common issue. Toyota issued a technical service bulletin on XXX covering this exactly. Some 2016–2019 Prius and 2017–2019 Prius Prime vehicles may exhibit low coolant level, MIL on with DTC P148F00, and/or poor heater performance due to coolant leakage at the front…
2019 Toyota Prius · Engine · filed with NHTSA Aug 26, 2026 · ODI 11759842
I purchased the car last July. Up to December, the car performed fine. Starting in December when I used the car heater repeatedly due to subzero temperatures, I noticed a burning smell coming from the vents. I was afraid that the engine or car would catch fire. I called the Tansky Toyota dealership and was told to bring the car in.
2022 Toyota RAV4 · Engine · filed with NHTSA Apr 22, 2023 · ODI 11518482
In depth: 2020 Toyota Camry engine problems → · 2019 Toyota Camry engine problems → · 2023 Toyota Corolla Cross engine problems → · 2020 Toyota RAV4 engine problems →
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 group69 other manufacturer communications filed against these Toyota models 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-0034-26 REV1 | Service bulletin | Sep 16, 2026 | Some 2025 – 2026 model year Camry HV vehicles may exhibit a MIL ON condition with Diagnostic Trouble Code (DTC) P0A1B94… |
| 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. |
| T-SB-0051-26 | Service bulletin | Aug 20, 2026 | This bulletin includes basic procedures for performing a rescue charge at battery on high voltage (HV) Ni-MH and Li-ion batteries. |
| 26TC03 | Service campaign | Aug 17, 2026 | In wet conditions, water contacting the radiator in the subject vehicles after idling for an extended period can create steam that can cause… |
| 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-TT-0806-26 | Service bulletin | Jul 22, 2026 | State of Health (SOH): An estimate of battery health that is updated as the vehicle learns from operating and charging conditions over time.… |
| T-SB-0034-26 | Service bulletin | Jun 30, 2026 | Some 2025 — 2026 model year Camry HV vehicles may exhibit a MIL on condition with DTC P0A1B94… |
| T-TT-0801-26 | Service bulletin | Apr 16, 2026 | Some Customers for the listed vehicles may have complaint of the following: unable to charge the vehicle using the supplied level 1 or 2 cha… |
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 T-TT-0784-25 REV1 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 T-TT-0784-25 REV1 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 T-TT-0784-25 REV1 cover?
The manufacturer filed it against 49 model years: 2022 Toyota Avalon, 2021 Toyota Avalon, 2020 Toyota Avalon, 2019 Toyota Avalon, 2025 Toyota Camry, 2024 Toyota Camry and more. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.