Recall 21V734 covers 8,411 2022 Toyota Prius Prime and Prius vehicles for ECU software that can shut down drive power. Free repair at Toyota dealers.
Toyota is recalling 8,411 2022 Prius Prime and Prius vehicles under recall 21V734 because Engine Control Unit software can falsely detect an error and shut down the hybrid system. That loss of drive power increases the risk of a crash, and Toyota dealers will update the ECU software free of charge.
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What's wrong?
The hybrid vehicle ECU in the 2022 Toyota Prius Prime and Prius is the computer that coordinates the hybrid propulsion system. It reads signals from the shifter and other controls, then tells the gasoline engine and electric drive system how to respond. The vehicle depends on that software to keep power flowing while the driver selects a gear and drives.
On affected vehicles, the ECU software has incorrect programming. If the shifter position status changes inside an approximately 0.1 millisecond window, the computer can falsely decide that the transmission shift position signal is wrong. That false error can shut down the hybrid system while the vehicle is moving, which causes a loss of drive power.
The warning sign is not a gradual change in how the car drives. Warning lights will illuminate, and the hybrid system will shut down. If that happens, the Prius or Prius Prime has already lost drive power and needs Toyota dealer attention under recall 21V734.
Who's affected?
The Prius Prime and Prius share the same hybrid vehicle ECU; the listed components are software and the hybrid propulsion system.
| 2022 Toyota Prius Prime | Software |
|---|---|
| 2022 Toyota Prius Prime | Hybrid propulsion system |
| 2022 Toyota Prius | Software |
| 2022 Toyota Prius | Hybrid propulsion system |
| Units affected | 8,411 |
The year and model narrow the scope, but the VIN decides. Check your VIN to confirm whether your specific car is included.
What's the safety risk?
A hybrid system shutdown can cause a loss of drive power, increasing the risk of a crash. If warning lights appear or the hybrid system shuts down, pull over when it is safe and arrange service. Schedule the ECU software update soon. Repair is free at any franchised Toyota dealer.
What should I do?
- Check your VIN to confirm your 2022 Toyota Prius Prime or Prius is included in this recall.
- Contact a franchised Toyota dealer to schedule the free ECU software update that prevents false hybrid-system shutdown and loss of drive power.
- Bring the owner letter if you have it, or reference recall number 21V734 and Toyota recall 21TB07/21TA07 when you call.
- Call Toyota customer service at 1-800-331-4331 with questions about scheduling or recall paperwork.
- Drive cautiously until the software update is complete, and leave extra space in traffic because the defect involves loss of drive power.
What happens at the repair
At the dealer, a Toyota technician updates the Engine Control Unit software that controls the hybrid system. The update is designed to stop the ECU from falsely detecting an error and shutting down the hybrid system. Parts and labor are covered under the recall, and the software update is free at a Toyota dealer. Ask the service desk to confirm that recall 21V734 is open for your VIN before the appointment.
Timeline
| September 22, 2021 | NHTSA published the recall |
|---|---|
| September 22, 2021 | Dealer notification began |
| September 22, 2021 | Dealer notification ended |
| November 18, 2021 | Owner notification mailed |
| November 20, 2021 | Interim owner notification (was planned for this date) |
Frequently asked questions
What is recall 21V734?
Recall 21V734 covers 8,411 2022 Toyota Prius Prime and Prius vehicles with ECU software that can falsely detect an error and shut down the hybrid system. That can cause a loss of drive power and increase crash risk.
What should I do if my 2022 Toyota Prius Prime or Prius is on this recall?
Check your VIN to confirm your specific vehicle is included in recall 21V734. If it is, contact a franchised Toyota dealer to schedule the ECU software update. Reference recall 21V734 or Toyota recall 21TB07/21TA07 when you call.
Is the recall repair free?
Yes. Federal recall law requires the manufacturer to repair the defect at no cost. Toyota dealers will update the ECU software free of charge at any franchised Toyota dealer.
What is the safety risk in recall 21V734?
The safety risk is loss of drive power. In recall 21V734, the ECU software can shut down the hybrid system after falsely detecting an error, which increases the risk of a crash.
What if I bought my Toyota Prius or Prius Prime used?
The free repair still applies. Federal recall law follows the vehicle, not the original owner. Check your VIN to confirm whether your specific 2022 Toyota Prius or Prius Prime is included, then call a franchised Toyota dealer for the free ECU software update.
More information
| NHTSA campaign page | nhtsa.gov/vehicle-recalls/21V734000 |
|---|---|
| Toyota customer service | 1-800-331-4331 |
| NHTSA recall # | 21V734 |
| NHTSA recall # (full) | 21V734000 |
Source documents
-
Download Recall Document (PDF) (PDF) - Download Quarterly Report (PDF)
- Download Misc. Document (PDF)
- Download Recall Investigation Document (PDF) (PDF)
- Download Owner Notification Letter (PDF)
- Download Owner Notice (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 →