Recall 18V921 affects 1,082 2017-2018 Honda Clarity Fuel Cell vehicles for FC-ECU software that can cause power loss. Repair is free at a franchised Honda dealer.
Honda is recalling 1,082 2017-2018 Clarity Fuel Cell vehicles that were already repaired under recall 18V921 because the earlier software fix was incomplete. The fuel cell control unit can read a small voltage drop incorrectly, causing partial or complete power loss, and Honda dealers will complete the repair free of charge.
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What's wrong?
The fuel cell control unit on the 2017-2018 Honda Clarity Fuel Cell is the computer that watches the fuel cell stack and manages propulsion power. The stack produces electricity from hydrogen and oxygen, and the control unit reads cell voltage to decide whether the system is operating within its limits.
These vehicles were repaired under recall 18V-068, but the software fix did not fully address this voltage-reading problem. In affected vehicles, slight deterioration in a pair of end cells can create a small combined voltage drop. The software can read that drop as broader fuel cell stack deterioration, then reduce or cut propulsion power instead of treating it as the specific cell issue.
The warning indicator will illuminate before the vehicle loses power. If that light appears, treat it as the warning sign connected to this recall and arrange dealer service.
Who's affected?
The scope is split by component: hybrid propulsion system and electrical system software are both listed for each model year.
| 2018 Honda Clarity Fuel Cell | Hybrid propulsion system |
|---|---|
| 2018 Honda Clarity Fuel Cell | electrical system software |
| 2017 Honda Clarity Fuel Cell | Hybrid propulsion system |
| 2017 Honda Clarity Fuel Cell | electrical system software |
| Units affected | 1,082 |
| Field incidents | NHTSA has logged no field incidents to date. |
The year and model narrow the scope, but the VIN decides. Check your VIN to confirm whether your specific sedan is included.
What's the safety risk?
A loss of power can increase the risk of a crash. If the warning indicator illuminates, drive cautiously, avoid unnecessary trips, and arrange the software update with a dealer soon. Repair is free at any franchised Honda dealer.
What should I do?
- Check your VIN to confirm your 2017-2018 Honda Clarity Fuel Cell is included in this recall.
- Contact a franchised Honda dealer to schedule the free FC-ECU software update that fixes the incomplete fuel-cell control software and addresses the loss-of-power risk.
- Bring the recall notice if Honda sent one. If not, reference recall number 18V921 and Honda recall A3O when you call.
- Drive cautiously until the update is complete. Leave extra room and pull over safely if the vehicle loses power.
- Call Honda customer service at 1-888-234-2138 with questions about the recall or dealer scheduling.
What happens at the repair
At the dealer, a Honda technician updates the FC-ECU software that controls fuel cell operation. The software update is free under the recall, and the campaign repair is available now. Honda is not offering a separate reimbursement program because the limited new vehicle warranty on all affected 2017-2018 Clarity Fuel Cell vehicles would have provided a free repair for this problem without owner payment. If you have prior repair paperwork, ask the service desk how the warranty applied to that visit.
| Reimbursement | Warranty coverage applies |
|---|
Timeline
| December 20, 2018 | NHTSA published the recall |
|---|---|
| December 21, 2018 | Dealer notification began |
| December 21, 2018 | Dealer notification ended |
| February 14, 2019 | Owner notification mailed |
| February 14, 2019 | VIN-searchable in NHTSA's database — Check your VIN to see whether this recall applies to your specific vehicle. |
| February 14, 2019 | Interim owner notification (was planned for this date) |
Frequently asked questions
What is recall 18V921?
Recall 18V921 covers 1,082 2017-2018 Honda Clarity Fuel Cell vehicles previously repaired under recall 18V-068 for an FC-ECU software remedy issue. The FC-ECU can misread a small cell voltage drop and cause partial or complete power loss, increasing crash risk. Honda dealers update the FC-ECU software for free.
What should I do if my 2017-2018 Honda Clarity Fuel Cell is on this recall?
Check your VIN to confirm your specific vehicle is included in recall 18V921. If it is, contact a franchised Honda dealer to schedule the FC-ECU software update. Reference recall number 18V921 and Honda recall number A3O when you call. The repair is free.
Is the recall repair free?
Yes. Federal recall law requires manufacturers to repair safety defects at no cost, and Honda dealers will update the FC-ECU software free of charge. This applies even if you bought the vehicle used or did not receive the original owner notice.
Is it safe to drive a Honda Clarity Fuel Cell with recall 18V921?
The risk is a partial or complete loss of power, which can increase the risk of a crash. Recall 18V921 is not listed as a do-not-drive recall, but you should confirm your VIN and schedule the free Honda dealer software update if your vehicle is included.
More information
| NHTSA campaign page | nhtsa.gov/vehicle-recalls/18V921000 |
|---|---|
| Honda customer service | 1-888-234-2138 |
| NHTSA recall # | 18V921 |
| NHTSA recall # (full) | 18V921000 |
Source documents
-
Download Misc. Document (PDF) - Download Recall Document (PDF) (PDF)
- Download Recall Investigation Document (PDF) (PDF)
- Download Owner Notification Letter (PDF)
- Download Owner Notice (PDF)
- Download Recall Report (PDF)
- Download Quarterly Report (PDF)
- Download Recall Acknowledgement (PDF)
This article is generated from NHTSA's primary recall filings and reviewed against the source on May 25, 2026. RecallNotify does not paraphrase NHTSA's consequence language; that text is reproduced as written above. Editorial standards →