Recall 21V468 affects 310 2017-2020 Alexander Dennis Enviro 500 buses for fuel-rail leaks. Repair will be free at any franchised Alexander Dennis dealer once available.
Alexander Dennis is recalling 310 2017-2020 Enviro 500 buses because a sealing washer can fail to seat correctly in the pilot bore holes and let the high pressure fuel rail assembly leak. A fuel leak near an ignition source increases the risk of a fire, and the Alexander Dennis dealer repair will be free once the remedy is ready.
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What's wrong?
The fuel rail on 2017-2020 Alexander Dennis Enviro 500 buses is part of the Cummins L9 diesel engine's fuel injection system. It holds diesel fuel under high pressure and feeds that fuel to the injectors, which meter fuel into the engine. Small sealing washers close the rail end openings so pressure stays inside the rail.
On affected buses, the pilot bore holes for those sealing washers were undersized. The washer does not sit fully in the bore, so the joint lacks the clamping load needed to stay sealed while the engine is in service. Diesel fuel then leaks from the high pressure fuel rail assembly instead of staying contained in the injection system.
Before failure, the operator can see diesel fuel, smell diesel fuel, or notice the check engine light. Those signs point to a fuel rail washer leak that needs dealer inspection.
Who's affected?
Spans four model years, all tied to the Cummins L9 diesel engine fuel rail.
| 2017 Alexander Dennis Enviro 500 | fuel system |
|---|---|
| 2019 Alexander Dennis Enviro 500 | fuel system |
| 2018 Alexander Dennis Enviro 500 | fuel system |
| 2020 Alexander Dennis Enviro 500 | fuel system |
| Units affected | 310 |
| Field incidents | NHTSA has logged no field incidents to date. |
A matching year and model does not guarantee inclusion. Check your VIN to confirm whether your specific bus is included.
What's the safety risk?
A diesel fuel leak in the presence of an ignition source increases the risk of a fire. Diesel fuel smell, visible fuel, or a check engine light are warning signs. If any of those appear, park safely and contact the dealer before continuing service. Repair will be free at any franchised Alexander Dennis dealer once available.
What should I do?
- Check your VIN to confirm your 2017-2020 Alexander Dennis Enviro 500 is included in this recall.
- Wait for Alexander Dennis repair instructions before scheduling dealer work.
- Contact Alexander Dennis customer service at 1-951-244-9429 with questions and reference recall number 21V468 when you call.
- Ask about the free fuel-rail inspection and rail replacement that addresses the high pressure fuel rail leak risk.
- Keep the bus away from ignition sources and service it promptly if you smell fuel or see a leak.
What happens at the repair
The final dealer repair is not open yet. Once available, an Alexander Dennis technician will inspect the rail threads and fuel lines, then replace the fuel rail if the inspection shows it is needed. Parts and labor will be free under the recall. Alexander Dennis says a specific reimbursement plan applies to units not covered by the manufacturer's limited warranty. If you already paid for a related fuel rail or fuel line repair, keep the repair paperwork and contact Alexander Dennis customer service about how that reimbursement plan applies.
| Reimbursement | Reimbursement available |
|---|
Timeline
| June 18, 2021 | Owner notification mailed |
|---|---|
| June 19, 2021 | Interim owner notification (was planned for this date) |
| June 23, 2021 | NHTSA published the recall |
Frequently asked questions
What is recall 21V468?
Recall 21V468 covers 310 2017-2020 Alexander Dennis Enviro 500 buses with a high-pressure fuel rail sealing washer that can sit incorrectly and allow a fuel leak. Alexander Dennis dealers will inspect the rail threads and fuel lines, then replace the rail if needed for free.
What should I do if my 2017-2020 Alexander Dennis Enviro 500 is on this recall?
Check your VIN to confirm your specific bus is included in recall 21V468. If it is, contact an Alexander Dennis dealer or Alexander Dennis customer service at 1-951-244-9429 to arrange the inspection and repair. Reference recall number 21V468 when you call.
Does the recall repair cost anything?
No. Federal recall law requires the manufacturer to repair the defect at no cost. Alexander Dennis dealers will inspect the fuel rail threads and fuel lines, and replace the rail if needed, free of charge.
What is the safety risk in recall 21V468?
The safety risk is fire. Recall 21V468 says a fuel leak near an ignition source increases the risk of a fire. Until your VIN is checked and the dealer repair is complete, ask the dealer how to handle the bus if you see or smell fuel.
When were owners notified about recall 21V468?
Alexander Dennis mailed owner notification letters on June 18, 2021. If you bought the bus used or never received a letter, the VIN still decides whether the recall applies. Check your VIN, then call an Alexander Dennis dealer with recall number 21V468.
More information
| NHTSA campaign page | nhtsa.gov/vehicle-recalls/21V468000 |
|---|---|
| Alexander Dennis customer service | 1-951-244-9429 |
| NHTSA recall # | 21V468 |
| NHTSA recall # (full) | 21V468000 |
Source documents
-
Download Recall Document (PDF) (PDF) - Download Quarterly Report (PDF)
- Download Recall Document (PDF) (PDF)
- Download Owner Notification Letter (PDF)
- Download Recall Report (PDF)
- Download Recall Acknowledgement (PDF)
This article is generated from NHTSA's primary recall filings and reviewed against the source on May 20, 2026. RecallNotify does not paraphrase NHTSA's consequence language; that text is reproduced as written above. Editorial standards →