Recall 21V532 affects 28 2021 New Flyer XD35 and XD40 buses for excessive ammonia emissions. Cummins engine recalibration is free.
New Flyer is recalling 28 2021 XD35 and XD40 vehicles equipped with 2021 Model Year Cummins L9 Diesel Engines because engine calibration software can allow excessive ammonia from the tailpipe exhaust. Exposure to high levels of ammonia can increase injury risk, and New Flyer dealers will complete the free repair.
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What's wrong?
The 2021 New Flyer XD35 and XD40 buses in this recall use a Cummins L9 diesel engine with an exhaust aftertreatment system. That system injects Diesel Exhaust Fluid into the exhaust stream to help control emissions before gases leave the tailpipe. The engine control module, or ECM, is the computer that tells the engine and emissions system how much fluid to use.
On affected buses, the ECM calibration uses too much Diesel Exhaust Fluid in the aftertreatment system. That over-dosing changes the exhaust chemistry and allows excessive ammonia to come out of the tailpipe. The difference between included and non-included engines is the ECM program revision level, so the repair is software-related rather than a broken pipe or muffler.
People around the bus can smell ammonia before the problem is identified. Treat that odor as the warning sign for this recall, especially near the tailpipe after the engine has been running.
Who's affected?
Covers both XD35 and XD40 buses from the 2021 model year, each tied to the L9 Cummins diesel exhaust system.
| 2021 New Flyer XD35 | Manifold/header/muffler/tail pipe |
|---|---|
| 2021 New Flyer XD40 | Manifold/header/muffler/tail pipe |
| Units affected | 28 |
| 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 bus is included.
What's the safety risk?
Exposure to high levels of ammonia increases the risk of injury for people near the vehicle. If anyone around the bus smells ammonia, move away from the vehicle and have the issue checked before continued service. Schedule the engine recalibration soon. Repair is free at any franchised New Flyer dealer.
What should I do?
- Check your VIN to confirm your 2021 New Flyer XD35 or XD40 is included in this recall.
- Contact a franchised New Flyer dealer to schedule the free engine recalibration that corrects the DEF injection software and ammonia exhaust issue.
- Bring the recall notice if New Flyer mailed one. If not, reference recall number 21V532 when you call.
- Call New Flyer customer service at 204-224-6706 with questions and ask about New Flyer recall R21-013.
- Keep riders and staff away from tailpipe exhaust until the software update is complete.
What happens at the repair
At the dealer, a New Flyer technician recalibrates the Cummins L9 engine software so the Diesel Exhaust Fluid injection system uses the corrected calibration. The software update is free under the recall, with parts and labor covered. New Flyer has a general reimbursement plan on file for qualifying out-of-pocket repairs paid before the recall notice. If you've already paid for a related engine calibration repair, bring your repair order and payment documentation to the service desk or contact New Flyer customer service.
| Reimbursement | Reimbursement available |
|---|
Timeline
| July 14, 2021 | NHTSA published the recall |
|---|---|
| July 19, 2021 | Dealer notification began |
| July 19, 2021 | Dealer notification ended |
| July 19, 2021 | Interim owner notification (was planned for this date) |
| July 23, 2021 | Owner notification mailed |
Frequently asked questions
What is recall 21V532?
Recall 21V532 covers 28 2021 New Flyer XD35 and XD40 buses equipped with 2021 model year Cummins L9 diesel engines. The engine calibration can inject diesel exhaust fluid in a way that lets excessive ammonia leave the tailpipe exhaust, increasing injury risk from ammonia exposure.
What should I do if my 2021 New Flyer XD35 or XD40 is on this recall?
Check your VIN to confirm your specific bus is included in recall 21V532. If it is, contact New Flyer customer service or an authorized service provider and reference New Flyer recall R21-013. Cummins will recalibrate the engine software for free.
Is the recall repair free?
Yes. Federal recall law requires manufacturers to repair safety defects at no cost, and Cummins will recalibrate the affected engine software free of charge. Parts and labor are covered for included 2021 New Flyer XD35 and XD40 vehicles.
What is the safety risk from this New Flyer recall?
The safety risk is ammonia exposure from tailpipe exhaust. The affected engine calibration allows excessive ammonia emissions from the diesel exhaust fluid system, and exposure to high levels of ammonia increases the risk of injury. The free engine recalibration is the repair path.
When were owners notified about recall 21V532?
New Flyer mailed owner notification letters on July 23, 2021. If you bought the bus after that date or never received a letter, check your VIN and reference recall 21V532 or New Flyer recall R21-013 when you contact service.
More information
| NHTSA campaign page | nhtsa.gov/vehicle-recalls/21V532000 |
|---|---|
| New Flyer customer service | 204-224-6706 |
| NHTSA recall # | 21V532 |
| NHTSA recall # (full) | 21V532000 |
Source documents
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 →