Toyota Recalled About 9 Million Vehicles Over Unintended Acceleration

Two official-sounding verdicts about the same Toyota cars sit uncomfortably side by side. In February 2011, after a 10-month search, scientists from NASA and the US safety regulator NHTSA announced that they had found no electronic defect behind the sudden unintended acceleration reports. In October 2013, a jury decided that deficiencies in the electronic throttle could have caused exactly that.

Between those two dates lay a recall campaign that reached about 9 million vehicles, paused sales of some of Toyota's most popular models and ended in a $1.2 billion penalty. Behind it all sits a plain question that every driver can understand: when a car surges and the brakes seem not to answer, is the fault in the machine or in the foot?

What is sudden unintended acceleration?

Sudden unintended acceleration, usually shortened to SUA, is a car gathering speed when the driver neither expects nor wants it, often with a feeling that the brakes have lost their grip. Causes range from driver error to mechanical or electrical faults. NHTSA estimates that 16,000 crashes a year in the United States happen because a driver reaches for the brake and hits the accelerator.

The regulator's own early definition was narrow. Its 1989 report on the subject described a burst of power from a standstill or very low speed, typically at the moment the driver moves the lever out of Park into Drive or Reverse. That report grew from a study begun in 1986, in which investigators examined ten vehicles that had drawn an above-average number of complaints and put the incidents down to driver error.

The limits of that study matter now. The newest car in it was a 1986 model, none of the vehicles had electronic throttle control and all were automatics. Modern cars, with an accelerator pedal that sends an electrical signal rather than pulling a cable, are believed to suffer their surges while already moving.

Shift patterns once played a part too. On 1950s General Motors cars with a column lever, Reverse sat at the far end of the arc with Low right beside it, so a driver looking backwards could easily select the wrong one and lurch forward. By the 1960s the familiar PRNDL order put Reverse well away from the forward gears, and Chrysler began dropping push-button drive controls from every model after 1965.

Two verdicts on the same cars: mechanical, not electrical in 2011, and possible software deficiencies in 2013.

How can a car accelerate when the driver does not want it?

There is no single route. The list of accepted mechanisms includes pedal misapplication, a pedal that physically cannot return, faults in the electronic throttle or its sensors, a throttle that sticks regardless of pedal position, tin whiskers, runaway in a diesel engine and the loss of braking effect in one-pedal driving modes.

Pedal misapplication is a driver error rather than a fault in the car. A shorter driver whose feet barely reach the floor can lack the reference points that tell the foot which pedal is which, and cramped layouts or an oversized accelerator make a mistake easier. An unresponsive pedal is a different matter: something blocks it, whether a foreign object or, in Toyota's case, a floor mat.

Think of a throttle as a tap. If the tap is stiff and you shove it harder, it can suddenly give way and open further than you meant. Throttle valves that grow sluggish or stick shut can do just that, which is why manufacturers sell cleaning sprays for them. Older carburettor cars had their own list of troubles, from weak return springs to cables that jumped their tracks.

Diesels have a failure of their own. Their power depends on the amount of fuel supplied, and if crankcase pressure becomes excessive it can push oil mist into the intake, where the engine burns it like fuel and runs away.

For drive-by-wire cars, a brake-accelerator interlock, sometimes called a smart throttle, would eliminate or at least curtail any surge that is not pedal misapplication, because it lets the brake override the throttle. A surge would then need that very mechanism to fail. It cannot be added to older cars that lack an electronic throttle.

Which other makes have faced unintended acceleration claims?

Toyota was not the first. Audi recalled 5000 models through the 1982 to 1987 model years over reports linked to six deaths and 700 accidents, at a time when NHTSA was looking at 50 models from 20 manufacturers. A 60 Minutes report broadcast on 23 November 1986, titled "Out of Control," showed an Audi surging with the brake pressed. It later emerged that the programme had not disclosed how the effect was produced: a canister of compressed air sat on the passenger floor, linked by a hose to a hole bored in the gearbox, all arranged by an expert working for a plaintiff in a pending lawsuit. Audi had argued all along that drivers were hitting the wrong pedal, and outside investigators reached that view.

Others followed. Reports in the 1986 Honda Accord, traced in NHTSA files to its Vehicle Speed Control component, date from 1988. Jeep Cherokees and Grand Cherokees were the subject of a March 1997 ABC News segment. Analyses of those Jeeps in the mid to late 1990s pointed to a leakage path for electric current that actuated the cruise control servo, throwing the throttle wide open as the lever moved from Park to Reverse. Many cases happened at car washes. A statistical study of 1991 to 1995 Jeeps concluded that human error could not be the root cause, contrary to what NHTSA and the manufacturers had long held.

A 2022 recall of the 2021 Ford Mustang Mach-E came because the powertrain control module's safety software might fail to detect an error, which could make the car surge, slow unexpectedly or lose drive.

How did the Toyota recalls begin?

The Toyota and Lexus incidents between 2000 and 2010 are the most prominent in the record, with up to 89 deaths and 52 injuries in the United States attributed to them. NHTSA first opened a defect investigation into Toyota in 2004 and its defects office closed it as inconclusive. Toyota's position was that its electronic controls could not fail in a way that produced a surge.

In April 2008, investigators found something concrete: on a 2004 Sienna, the driver-side trim could work loose and stop the accelerator pedal returning fully. The floor mat was next. On 26 September 2007, Toyota had already recalled 55,000 optional all-weather rubber mats in the Camry and ES 350 because unsecured mats could slide forward and trap the pedal.

The turning point came on 28 August 2009 in San Diego, when a two-car collision killed four people in a Lexus ES 350 loaned out by a dealer. NHTSA's report, published on 25 October, found the car fitted with all-weather mats designed for the RX 400h SUV and not held down by either retaining clip. The pedal was still bonded to the mat, and its return spring moved smoothly. The brake hardware showed signs of heavy braking. The report added that the pedal hinge could not release an obstruction and that the dashboard gave no instruction for the three-second press needed to shut off a push-button keyless ignition.

A separate county sheriff's investigation found that the dealership had already heard from another customer, three days before the crash, about a mat trapping the accelerator of that same loaner. That earlier driver had shifted to neutral and tugged the mat free.

What did the Toyota recall of 2009 cover?

On 2 November 2009 Toyota recalled 3.8 million vehicles and told owners to take out the driver's mat and fit nothing in its place. The same day, NHTSA turned down a petition to reopen its earlier Toyota investigations, saying they had been thorough. Toyota's announcement appeared to blame the mats alone, and the regulator answered that the matter was not closed until Toyota addressed the defect, calling the letter inaccurate and misleading and the mat removal an interim step.

The affected list ran across the range: the Avalon, Camry, Corolla, Highlander, Matrix, Prius, Tacoma, Tundra and Venza, the Lexus ES 350 and IS 250, and the Pontiac Vibe, a General Motors rebadge of the Matrix. Toyota UK stated that the mat recall concerned US models only.

Toyota amended the action in late November 2009. The remedy had three parts: shave the accelerator pedal to reduce the risk of entrapment, swap all-weather mats for a thinner design, and fit a brake override that cuts engine power if both pedals are pressed. That system, also called brake to idle, was by then common in German cars. Owners who did not want the new mat were reimbursed. Installation of the override began in January 2010 on the Camry and ES 350, the largest groups in the recall.

What was the Toyota sticky pedal recall of 2010?

On 21 January 2010 Toyota opened a second front. Some crashes had occurred in cars without floor mats, and the company had received three complaints in 2009 of pedals sticking. The recall covered 2.3 million vehicles sold in the United States. Toyota described the fault as rare and gradual, a worn mechanism that could make the pedal harder to press, slower to return or, at worst, stuck partly down. NHTSA's name for it was the Sticky Pedal Recall, and its advice for a driver with a stuck pedal was to shift to neutral and stop.

Europe and China followed, with 1.8 million vehicles and 75,000 respectively, taking the worldwide total to 9 million. Toyota suspended sales of selected vehicles on 26 January until a final remedy existed. The Wall Street Journal reported on 31 January that US regulators had cleared the pedal repair, with production due to resume by 8 February, and on 1 February Toyota said dealers should have parts by the end of that week.

The counting is untidy. By 28 January there were 5.2 million vehicles in the mat recall and 2.3 million in the pedal recall, with roughly 1.7 million in both.

Toyota recall timeline

Not every Toyota recall in that stretch was about acceleration. Through 2010 the company also recalled 7,300 Camrys over brake tubes, 8,000 Tacoma pick-ups over front drive shafts, 600,000 Siennas over a spare tyre cable, 270,000 Crown and Lexus models over valve springs and 412,000 Avalons and LX 470s over steering column parts. A further 21,000 Land Cruiser Prados and 13,000 Lexus GX 460s went back to have their stability control reprogrammed.

How many deaths were blamed on Toyota acceleration?

The figure moved fast. In January 2010, 21 deaths since 2000 were alleged to be due to the pedal problem. After the 28 January recall brought a surge of further complaints to NHTSA, the alleged total rose to 37. Heavy US media coverage fed the rise, and the cause behind each report was hard to verify. Officials, experts, Toyota and members of the public disputed how large the problem was and how reliable the reports were.

Some owners whose cars had been repaired still reported trouble with the accelerator, which led to further investigations and the discovery of improper repairs. The recalls also brought more inquiries by NHTSA and Toyota, and a run of lawsuits.

What did NASA and NHTSA conclude?

On 8 February 2011, NHTSA and NASA published their findings on Toyota's drive-by-wire throttle. After a 10-month search, they found no electronic defect. Driver error or pedal misapplication accounted for most incidents, and the report's own line was blunt: Toyota's problems were mechanical, not electrical, meaning sticking pedals and pedals caught under floor mats. Two weeks later, Toyota recalled a further 2.17 million vehicles for pedals that become trapped on floor hardware.

Why did a jury later disagree?

Not everyone accepted that finding. A jury sided against Toyota on 24 October 2013, finding that flaws in the electronic throttle control system could have produced a surge. Michael Barr, of the Barr Group, told the court that NASA's examination of that system was never completed, and that Toyota had not followed best practice for real-time software on which lives depend.

He raised two specific risks. A single flipped bit in memory, which a cosmic ray could cause, might be enough to trigger acceleration. And the real-time operating system's memory stack was too small, so it could swell enough to overwrite other data. Toyota entered settlement talks with the plaintiffs after the verdict.

A deal with the US Department of Justice followed in March 2014. It was a deferred prosecution agreement carrying $1.2 billion of financial penalties. According to later findings, Toyota had known about the problems, misled consumers and gone on building defective cars.

Could electronics really cause a surge?

Laboratory work says it is possible in some modern cars. In one replication, a drop in voltage down to 7V rebooted the engine computer, and the throttle position reached 100% while the physical pedal was still held at 37%. A camera placed inside the engine confirmed the throttle really had opened fully, and the logs showed nothing abnormal. On the road, the same conditions produced a sudden surge four hours into the study.

On the Toyota side, a 2011 analysis found a significant number of tin whiskers, needle-like growths of pure tin, on accelerator pedal position sensors that used tin finishes. A 2013 study of an engine computer from a 2008 Tundra found pure tin over a nickel layer on a connector, and whiskers grew on it under temperature and humidity cycling. A 2005 Camry incident that was first blamed on a tin whisker was later proven not to be one.

In January 2021, engineer Colin O'Flynn induced unintended acceleration on a bench using electromagnetic fault injection, with a computer and parts from a wrecked 2005 Corolla. He worked with no access to the program code and no sight of the confidential Barr Group report.

What does this mean for drivers?

The record gives a few plain lessons. The San Diego car shows why floor mats must be the right ones, clipped down. A brake override, now familiar from the Toyota fix and from German cars, means pressing the brake cuts the engine power. If a pedal does stick, NHTSA's advice was to shift to neutral and stop. And in a car with a push-button start, investigators noted, an emergency shutdown takes a three-second press.

Is unintended acceleration still an issue?

The remedy engineers describe for electronic surges is the brake override: with one fitted, a surge would need that mechanism to fail as well, though it cannot be retrofitted to older cars without an electronic throttle. For newer cars the concern has moved towards software. Ford's 2022 recall of the Mustang Mach-E over powertrain safety software shows the issue is still live, and Colin O'Flynn's 2021 bench demonstration shows that researchers are still probing engine computers for ways to provoke a surge. Toyota's own case rests on two readings of the same cars, the 2011 finding that the faults were mechanical and the 2013 verdict that the software could have been at fault.