Honda bulletin A21-084
What it saysThe MIL comes on with DTC P1F86 FC Cell Voltage Too Low (Caution). NHTSA’s full summary ↓
Honda filed this with NHTSA as a service bulletin dated Dec 16, 2021, received Nov 2, 2021, about the engine — 2 documents under this number. It names 3 model years (2019–2021). 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 communicationService Bulletin - The MIL comes on with DTC P1F86 FC Cell Voltage Too Low (Caution).
Trouble codes it names: P1F86
Documents filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| A21-084 | Service bulletin | Dec 16, 2021 | 10205454 | PDF, 2,031 KB |
| A21-084 | Service bulletin | Oct 26, 2021 | 10202872 | PDF, 2,029 KB |
What the document itself lists
Part the bulletin names
| Part number | Description | Qty | Find it |
|---|---|---|---|
| 21232-RCT-A00 | — | 1 |
Labour operations and the time the manufacturer allows
| Operation | Description | Time |
|---|---|---|
| 3101CK | Replace the Fuel Stack and Ion Filter – (Includes control unit update) | 11.2 hrs |
| A21084A | 3A100-5WM-A50 3120A0 Venting (Clarity FC) | 1.7 hrs |
| 3120A0 | Venting (Clarity FC) | 1.7 hrs |
| A21084D | 3A100-5WM-A61 3120A0 Venting (Clarity FC) | 1.7 hrs |
Read by machine from the document NHTSA serves (23 pages), read Oct 4, 2026. A part number is shown only where it matches Honda’s own catalogue shape, an operation only with its code and time, and a description only where the reader got it whole; anything it could not settle is left out, and the PDF is the record. Times are the manufacturer’s warranty allowances, not a quote. Listings and prices on eBay Motors are the seller’s.
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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 3 model years this bulletin names have filed 60 complaints with NHTSA since 2015. 14 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.
When driving in gas mode, the engine is revving high as in high rpm . I am not sure if the gear is shifting or has problems. The car revs high and the more I push the accelerator the louder the engine sound
2019 Honda Clarity · Engine · filed with NHTSA Jan 23, 2023 · ODI 11503147
Engine RPM's rise (near red line at times) with little to no propulsion. The slang I've found used in online forums, showing that this is a common problem, is "angry bees."
2020 Honda Clarity · Engine · filed with NHTSA Dec 23, 2022 · ODI 11498681
The engine revs a lot when battery charge is low the engine and transmision gets very loud car has only 500 miles and is doing it constant
2021 Honda Clarity · Engine · filed with NHTSA Dec 29, 2020 · ODI 11385537
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.
Quote the number at the service desk. It is what the dealer’s system is keyed on.
Every manufacturer communication NHTSA holds for Honda, by the number printed on the letter.
Common questions
Source: NHTSA, 49 CFR 579.5Is Honda A21-084 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 A21-084 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 Honda warranty extension on file lists the ones Honda has filed.
Which vehicles does A21-084 cover?
The manufacturer filed it against 3 model years: 2021 Honda Clarity, 2020 Honda Clarity, 2019 Honda Clarity. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.