2022 Toyota Prius Engine Control Module Software Recall (21V734)
Toyota Motor Corporation · 8,411 vehicles · Reported September 22, 2021
Toyota Motor Corporation is recalling 8,411 2022 Toyota Prius; 2022 Toyota Prius Prime vehicles. The Engine Control Unit (ECU) software may falsely detect an error and shut down the hybrid system, causing a loss of drive power. A loss of drive power increases the risk of a crash. Dealers will make the repair free of charge.
Recall 21V734 at a glance
| NHTSA campaign number | 21V734000 |
|---|---|
| Manufacturer recall number | 21TB07 / 21TA07 |
| Date reported to NHTSA | September 22, 2021 |
| Manufacturer | Toyota Motor Corporation |
| Vehicles | 2022 Toyota Prius; 2022 Toyota Prius Prime |
| Units affected | 8,411 |
| Component | Engine And Engine Cooling > Engine > Engine Control Module (Ecu / Ecm) > Software |
| Safety risk | A loss of drive power increases the risk of a crash. |
| Fix | Available at dealers |
What is wrong with the 2022 Toyota Prius in recall 21V734?
The Engine Control Unit (ECU) software may falsely detect an error and shut down the hybrid system, causing a loss of drive power.
Toyota Motor Engineering & Manufacturing (Toyota) is recalling certain 2022 Prius and Prius Prime vehicles. The Engine Control Unit (ECU) software may falsely detect an error and shut down the hybrid system, causing a loss of drive power.
Is it safe to drive a 2022 Prius with recall 21V734?
NHTSA has not told owners to stop driving, but the risk is real: A loss of drive power increases the risk of a crash.
NHTSA describes the risk this way: A loss of drive power increases the risk of a crash.
There is no do-not-drive order on this campaign. If your Prius shows warning lights or behaves differently in a way that involves the software, have it checked before driving further.
Which vehicles are included in recall 21V734?
Recall 21V734 covers 8,411 vehicles: 2022 Toyota Prius; 2022 Toyota Prius Prime.
NHTSA lists 8,411 vehicles in this campaign. Not every vehicle of these models and years is included, so check your VIN.
| Model years | Make | Model |
|---|---|---|
| 2022 | Toyota | Prius |
| 2022 | Toyota | Prius Prime |
What is the fix for the Prius engine control module software recall?
Yes. Dealers will update the ECU software, free of charge.
Dealers will update the ECU software, free of charge. Owner notification letters were mailed November 18, 2021. Owners may contact Toyota customer service at 1-800-331-4331. Toyota's number for this recall is 21TB07/21TA07.
Manufacturer recall number: 21TB07 / 21TA07.
When was recall 21V734 announced?
Toyota Motor Corporation reported recall 21V734 to NHTSA on September 22, 2021. NHTSA lists the owner letter date as November 18, 2021.
| Date | What happened |
|---|---|
| September 22, 2021 | Toyota Motor Corporation filed the defect report with NHTSA; NHTSA assigned campaign 21V734000. |
| November 18, 2021 | Owner notification letters mailed (per NHTSA). |
This recall was filed 61 months ago. If your Prius was built in that window, the VIN check below is the way to confirm it is included.
How do I check if my Prius is part of recall 21V734?
Enter your 17-character VIN at nhtsa.gov/recalls. If recall 21V734 is open on your Prius, it will be listed there.
Enter your 17-character VIN at NHTSA’s recall lookup. It shows any open safety recall on your vehicle, including 21V734000. Your VIN is on the registration card, the insurance card, and the driver side of the dashboard where it meets the windshield. Recent recalls can take a few days to appear in the lookup.
What should Prius owners do about recall 21V734?
Check your VIN, schedule the free recall repair, and keep a repair order for every dealer visit.
- Check your VIN at nhtsa.gov/recalls to confirm recall 21V734000 applies to your Prius.
- Call a Toyota dealer and schedule the recall repair. Ask how long the repair takes and whether parts are in stock.
- Keep a copy of every repair order. Check that each one lists your complaint, the mileage, and the dates in and out.
- Write down when symptoms involving the software happen: date, mileage, speed, weather and what you felt or heard. Photos and short videos help.
- Count the days the vehicle is at the dealer. Days out of service add up toward California's 30-day presumption.
- If the problem comes back after the repair, return to the dealer and contact a lemon law attorney.
What are Prius owners reporting to NHTSA?
Owners have filed 32 complaints with NHTSA about these vehicles since 2020, 4 of them about the engine.
Too few NHTSA complaints about the engine have been filed since recall 21V734 was reported (4) to say whether the fix is holding.
NHTSA’s public complaint database lists 32 owner complaints filed since 2020 for the vehicles in this recall, and 4 of them involve the engine. Complaints are reports from owners and have not been verified by NHTSA, but a high count for the same component is a sign the problem is widespread.
- 2022 Toyota Prius: 24 complaints in total, 3 about the engine
- 2022 Toyota Prius Prime: 8 complaints in total, 1 about the engine
Here is what some owners told NHTSA, in their own words (excerpts, unverified):
The contact owns a 2022 Toyota Prius Prime. The contact stated while depressing the accelerator pedal, the vehicle failed to accelerate as intended. The contact stated multiple unknown warning lights had been temporarily illuminated. The vehicle was taken to a local dealer however, the cause of the failure could not be determined.
2022 Toyota Prius Prime owner, AL, NHTSA complaint 11596391, filed June 25, 2024
My 2022 Prius LE hood latch does not work. It does not click and hood stays locked. They told me at Walmart that the hood latch is probably corroded somewhere or defective. It takes two people to open the hood. My vehicle has 54,490mi. This has happened twice now in 2 months.
2022 Toyota Prius owner, TX, NHTSA complaint 11678882, filed August 6, 2025
Carfax notified us that our vehicle was part of a recall on 9/24/21. Toyota never contacted us. I contacted Toyota Corporate the week of Oct. 18th and they contacted the dealer (Hudson Toyota in Jersey City) and the dealer said they had a fix.
2022 Toyota Prius owner, NJ, NHTSA complaint 11438940, filed November 1, 2021
Can recall 21V734 make my Prius a lemon in California?
Not by itself. A recall repair that fails, or repeat dealer visits for the same defect, can support a California lemon law claim.
Recall 21V734000 does not automatically make your Prius a lemon. California's Song-Beverly Act asks two questions: does a warranty defect substantially impair the vehicle's use, value or safety, and did the manufacturer fail to fix it in a reasonable number of tries (Civ. Code 1793.2(d))?
Engine defects can mean stalling, loss of power, oil consumption or overheating. When the same engine complaint brings the 2022 Toyota Prius back to the dealer more than once, that history matters under California's lemon law.
The recall repair is available at dealers. If it works, great. If the same symptom comes back, the recall visit is one repair attempt and the next visit is another.
California law presumes a reasonable number of attempts has been made if, within 18 months or 18,000 miles of delivery, the same problem was repaired two or more times for a defect likely to cause death or serious injury, four or more times for any covered defect, or the vehicle was out of service for repairs more than 30 days in total (Civ. Code 1793.22(b)). Some of these require written notice to the manufacturer. A claim can still succeed outside that window.
An owner who prevails in a lemon law case can recover reasonable attorney fees and costs from the manufacturer (Civ. Code 1794(d)). You pay nothing, win or lose. We are paid only if you win, and the manufacturer pays our fees, including in settlements. If a case is lost, our firm covers the costs.
In our cases, a recall repair visit counts as a repair attempt, and it's strongest when the owner complained about the problem before the recall came out. A recall shows the defect is real and that enough owners reported it for the manufacturer to issue a fix.
A software update can count as a repair attempt, especially if you complained about the problem or the update keeps being repeated. I've seen dealers do the same software update five or six times with no fix.
A typical pattern: an owner reports the transmission slipping, and the dealer can't verify it. Six months later, NHTSA issues a recall for the same problem. Because the recall confirms the defect, the mileage offset goes back to that first visit.
The biggest mistake I see is waiting too long. The mileage offset starts at your first repair visit for the problem, so the sooner you take it in, the better. If the problem comes and goes, take it in when it happens. You can't go back to that date later.
If you get a recall notice, call a lemon law attorney right away. You may have taken the car in for the same problem before and forgotten, or there may be other recalls related to it.
Jacob Shayesteh, Esq. (SBN 362320), Founder and Managing Attorney. Quotes lightly edited for clarity. Prior results do not guarantee a similar outcome.
Has your Prius been back to the dealer for this problem?
Call 877-536-6620Other Toyota Prius recalls
Frequently asked questions about recall 21V734
Is the 21V734000 recall repair free?
Yes. Safety recall repairs are done free of charge at authorized dealers.
When will owners be notified?
According to NHTSA, owner notification letters were or are scheduled to be mailed November 18, 2021.
How do I know if my Prius is part of recall 21V734000?
Enter your 17-character VIN in NHTSA's recall lookup at nhtsa.gov/recalls, or call a dealer. The VIN is on your registration, insurance card and the lower corner of the windshield.
Does a recall mean my car is a lemon?
Not on its own. A lemon law claim depends on whether a covered defect keeps coming back or keeps the vehicle out of service. A recall repair that fails, or repeat visits for the same problem, can support a claim.
What should I keep for a possible lemon law claim?
Keep every repair order, the recall owner letter, your purchase or lease contract, and notes on dates, mileage and symptoms. Make sure each dealer visit is written up, even when the dealer says it cannot find a problem.
Does the recall fixing my car mean I have no case?
Not necessarily. Even if the recall repair fixed it, you may still have a case, and a car that's a year or more old can still qualify.
Do used cars qualify for California lemon law?
We take certified pre-owned, demo and dealer vehicles. Since the California Supreme Court's Rodriguez decision in 2024, ordinary used cars generally do not qualify.
How long does a recall lemon law case take?
Recall-related cases typically resolve in one to three months from your first call. Prior results do not guarantee a similar outcome.
What does a lemon law attorney cost?
You pay nothing, win or lose. We are paid only if you win, and the manufacturer pays our fees, including in settlements. If a case is lost, our firm covers the costs.
Sources
- NHTSA recall record 21V734000 (recall report and owner letters are posted there)
- NHTSA complaints and recalls data, accessed October 1, 2026
- California Civil Code 1793.2 and 1793.22
Attorney advertising. America’s Lemon Lawyer is a trade name of Wynn Law Group, APC. Responsible attorney: Jacob Shayesteh, Esq. (SBN 362320). This page is general information, not legal advice. America’s Lemon Lawyer is not affiliated with NHTSA or Toyota. Prior results do not guarantee a similar outcome.