California class action alleges 2010-2014 Toyota Prius cars enter fail-safe modes and stall.

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Toyota Prius Inverter Failure Lawsuit Moves Forward
California class action alleges 2010-2014 Toyota Prius cars enter fail-safe modes and stall.

— A Toyota Prius inverter failure class action lawsuit will move forward after a federal judge refused to dismiss most of the claims.

The class action lawsuit is two suits combined for California customers of 2010-2014 Toyota Prius hybrid cars that enter "fail-safe" mode or completely stall due to overheated inverters.

According to the lawsuit, Prius cars sold between 2004 and 2009 used hybrid inverter assemblies that contained intelligent power modules (IPMs) with boost converters to increase the the voltage of the hybrid systems. The converters kick in under high-load driving conditions, and transistors convert the voltage from direct to alternating current.

The inclusion of a boost converter enabled Toyota to reduce the size of the car’s battery and generate more power by increasing the maximum voltage to 500 volts during “high-load” driving conditions. The lawsuit says the additional voltage increases the power of the motor, but it generates a lot more heat within the IPM.

Toyota allegedly modified the hybrid inverter assembly in the Toyota Highlander and the Lexus RX400, but whereas the boost converter in the Prius increased voltage to a maximum of 500 volts, the boost converter in the Highlander and RX400 hybrids increased the voltage to a maximum of 650 volts.

The plaintiffs allege that in 2005 and 2006, Toyota allegedly discovered heat fluctuations can crack the solder that attaches the transistors to the IPM control board. Cracks in the solder leave air voids that reduce the ability to dissipate heat, which damages the transistors and causes the IPM to malfunction and fail.

Even knowing the problems caused by boosting the operating voltage from 500 to 650 volts, Toyota allegedly still chose to do just that with 2010-2014 Prius models. However, the automaker didn't inform the buying public of the changes and the dangers caused by overheated inverters, not until the cars were recalled for stalling due to IPM failures.

According to the lawsuit, the recall repairs didn't fix the problem of deformed transistors that caused the inverter problems, but Toyota instead chose to simply reflash the software to ensure the cars entered fail-safe mode instead of shutting off completely. In addition, the plaintiffs claim the reflash caused more problems with engines that suddenly were sluggish.

Toyota is allegedly aware of the serious inverter problems because the automaker issued an extended warranty for inverter repairs for Prius cars that had the software reflashed. Toyota also ordered another recall in 2018 for cars prone to inverter failures which could “result in the hybrid system shutting down rather than going into fail-safe mode.”

Toyota filed a motion to dismiss the class action, but the judge found most of the arguments unpersuasive.

A big ruling from the judge came when she found that assuming the allegations against Toyota are true, there is evidence the automaker knew of the IPM defect at the time the cars were sold.

The judge also refused to dismiss implied warranty, Song-Beverly Act and federal warranty claims. Additionally, other claims that will move forward include unjust enrichment and injunctive relief. However, the automaker did succeed in convincing the judge to dismiss a claim for express warranty violations.

The Toyota Prius inverter failure class action lawsuit was filed in the U.S. District Court for the Central District of California - Remy McCarthy et al., v. Toyota Motor Corporation, et al.

The plaintiffs are represented by Beasley, Allen, Crow, Methvin, Portis, & Miles PC, Cuneo Gilbert & LaDuca LLP, DiCello Levitt & Casey, and Fazio Micheletti LLP. has complaints submitted by owners of Toyota Prius cars.

Toyota Prius - 2010 / 2011 / 2012 / 2013 / 2014


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