Incident: Toyota Prius Recall Due to Programming Glitch in Hybrid System

Published Date: 2010-02-05

Postmortem Analysis
Timeline 1. The software failure incident involving the recall of all 1.9 million third-generation Prius cars due to a programming glitch in their hybrid system happened in February 2014 as reported in [Article 24237] and [Article 24637].
System 1. Boost converter software in the hybrid system of the third-generation Prius cars [24237, 24637] 2. Software controlling critical car functions in the 2010 Toyota Prius [498]
Responsible Organization 1. Toyota Motor Corp was responsible for causing the software failure incident in the Prius vehicles due to a programming glitch in their hybrid system [24237, 24637]. 2. Ford Motor Co was also responsible for causing a software failure incident in the Mercury Milan and Ford Fusion gas-electric hybrids due to a glitch in the braking system software [498].
Impacted Organization 1. Toyota Motor Corp [24237, 24637] 2. Prius owners worldwide [24237, 24637]
Software Causes 1. The software cause of the failure incident was a programming error in the hybrid system software of the third-generation Prius vehicles, leading to a potential shutdown of the gas-electric hybrid systems [24237, 24637]. 2. Another software cause was a glitch in the software used to control the boost converter in a module of the hybrid system, resulting in higher thermal stress in certain transistors and potential system shutdowns [24637]. 3. Software settings on the newest Prius generation could stress and damage transistors in the hybrid systems, leading to warning lights, fail-safe mode activation, and potential shutdowns while driving [24237].
Non-software Causes 1. Mechanical rods and cables being replaced by electronics in vehicles, leading to potential risks [498]. 2. Accelerators getting trapped under floor mats or stuck on their own in non-hybrid Toyota cars, causing failures [498]. 3. Concerns about electromagnetic interference affecting automobile engines [498]. 4. Issues with the antilock braking system causing inconsistent brake feel on rough or slick road surfaces [498].
Impacts 1. The software failure incident in Toyota's Prius vehicles led to a recall of all 1.9 million third-generation Prius cars sold worldwide due to a programming glitch in their hybrid system [24237, 24637]. 2. The recall affected approximately 713,000 Prius vehicles in North America and half of the recalls were in Japan [24237, 24637]. 3. The software error could cause the hybrid system to shut down, resulting in the vehicle coming to a stop while being driven, potentially leading to safety risks [24237, 24637]. 4. The recall could damage the Prius's reputation as a global leader in hybrid technology and could have implications beyond the 1.9 million owners affected [24237]. 5. Toyota's proactive approach to issuing recalls, even for minor problems, has been highlighted as a response to the software failure incident, showcasing a shift in the company's approach to safety issues [24237]. 6. The incident underscores the growing complexity of modern vehicles, which are increasingly reliant on technology and electronic systems, making them more susceptible to software glitches and problems [24237]. 7. The software failure incident adds to Toyota's ongoing quality problems and legal issues, impacting the company's reputation and potentially leading to financial costs associated with the recalls and settlements [24237].
Preventions 1. Implementing a brake override system that shuts off the fuel supply to the engine if the brakes are engaged and the accelerator is down could have prevented the software failure incident [498]. 2. Conducting more extensive testing in different conditions to ensure the software's reliability and safety [498]. 3. Enhancing the design and functionality of the push-button ignition system to allow for easier and quicker engine shutdown in emergencies [498]. 4. Improving the software controlling critical car functions to prevent issues such as brake lights lighting up for no reason and gasoline engines shutting down unexpectedly [498].
Fixes 1. Updating the software settings on the newest Prius generation to prevent stress and damage to transistors in the hybrid systems [24237, 24637]. 2. Implementing changes on the assembly line to prevent inconsistent brake feel during slow and steady application of brakes on rough or slick road surfaces [498]. 3. Conducting a software fix for the glitch in the Ford Fusion gas-electric hybrids that gives drivers the impression the brakes have failed [498].
References 1. Press releases from Toyota Motor Corp [Article 24237, Article 24637] 2. Statements from Toyota spokespeople [Article 24237, Article 24637] 3. National Highway Traffic Safety Administration (NHTSA) reports [Article 498]

Software Taxonomy of Faults

Category Option Rationale
Recurring one_organization, multiple_organization (a) The software failure incident having happened again at one_organization: - Toyota experienced a software failure incident with its Prius vehicles due to a programming glitch in their hybrid system, leading to a recall of 1.9 million third-generation Prius cars sold worldwide [24237, 24637]. - This is not the first time Toyota has faced software-related issues with its vehicles. In the past, Toyota had recalls related to software problems, such as brake lights lighting up for no reason and gasoline engines shutting down due to software controlling critical car functions [498]. (b) The software failure incident having happened again at multiple_organization: - The article mentions that Ford Motor Co. also faced a software-related issue with its gas-electric hybrids, specifically the Mercury Milan and Ford Fusion models, where a glitch could give drivers the impression that the brakes have failed [498]. - The broader context of the automotive industry shows that car manufacturers, in general, have faced challenges with software-related issues in their vehicles, indicating a common trend of software failures across multiple organizations [498].
Phase (Design/Operation) design, operation (a) The software failure incident related to the design phase is evident in the articles. The incident with Toyota's Prius vehicles was caused by a programming error in the hybrid system software. Toyota mentioned that the problem was in the software used to control the boost converter in a module that is part of the hybrid system, leading to higher thermal stress in certain transistors within the booster converter, potentially causing them to deform or become damaged [Article 24637]. This highlights a failure due to contributing factors introduced during the system development phase. (b) The software failure incident related to the operation phase is also apparent in the articles. In the case of the Prius recall, Toyota stated that the setting of the software could cause higher thermal stress in certain transistors within the booster converter, leading to various warning lights being illuminated and possibly causing the vehicle to enter a failsafe mode. In limited cases, the hybrid system could shut down, causing the vehicle to stop, possibly while it is being driven [Article 24637]. This indicates a failure due to contributing factors introduced by the operation or misuse of the system.
Boundary (Internal/External) within_system, outside_system (a) within_system: The software failure incident related to the Toyota Prius recall was due to a programming error in the hybrid system software. Toyota mentioned that the problem was in the software used to control the boost converter in a module that is part of the hybrid system, causing higher thermal stress in certain transistors within the booster converter, leading to various warning lights being illuminated and possibly causing the vehicle to enter a failsafe mode [Article 24637]. (b) outside_system: The broader issues affecting Toyota, including problems with accelerators getting trapped under floor mats or becoming stuck, were related to mechanical issues rather than software failures. Transportation Secretary Ray LaHood mentioned a review of whether automobile engines could be disrupted by electromagnetic interference caused by external sources like power lines [Article 498].
Nature (Human/Non-human) non-human_actions (a) The software failure incident occurring due to non-human actions: - In the incident involving Toyota's Prius recall, the software failure was attributed to a programming error that could cause the gas-electric hybrid systems to shut down. This issue was related to a software glitch in the hybrid system, specifically in the software used to control the boost converter, leading to thermal stress in certain transistors within the booster converter [Article 24237, Article 24637]. (b) The software failure incident occurring due to human actions: - The articles do not mention any specific human actions contributing to the software failure incident. The focus is primarily on the technical aspects of the software glitch and the implications for the vehicles involved.
Dimension (Hardware/Software) hardware, software (a) The software failure incident occurring due to hardware: - Article 24237 mentions that Toyota is recalling all 1.9 million newest-generation Prius vehicles due to a programming error that could cause their gas-electric hybrid systems to shut down. The issue is related to problems in software settings that could stress and damage transistors in the hybrid systems, leading to the hybrid system shutting down while the vehicle is being driven [24237]. - Article 24637 also highlights that the recall is due to a programming glitch in the hybrid system, specifically in the software used to control the boost converter in a module that is part of the hybrid system. This glitch could cause higher thermal stress in certain transistors within the booster converter, resulting in various warning lights being illuminated and possibly causing the vehicle to enter a failsafe mode [24637]. (b) The software failure incident occurring due to software: - Article 498 discusses how advancements in car technology have shifted from mechanical controls to electronic sensors and computers governing various functions in vehicles. It mentions that Toyota faced issues with its Prius models, including problems with the brake accumulator and accelerator issues in non-hybrid cars, which were more conventional mechanical issues. However, the article also points out that the Prius had an electronically operated braking system as part of its hybrid design, which could lead to potential failures due to the increased complexity of the car and the number of potential failures, indicating a software-related aspect [498]. - Additionally, Article 498 mentions that Toyota had previously recalled Priuses in 2005 due to reports of brake lights lighting up for no reason and gasoline engines shutting down on their own accord, with the culprit being the software controlling critical car functions. This indicates a software-related issue leading to the recall [498].
Objective (Malicious/Non-malicious) non-malicious (a) malicious: There is no information in the provided articles indicating that the software failure incident related to the Toyota Prius recall was malicious in nature. The incident was attributed to a programming error in the hybrid system software, leading to potential shutdowns and warning lights in the vehicles [24237, 24637]. (b) non-malicious: The software failure incident related to the Toyota Prius recall was non-malicious in nature. It was caused by a programming glitch in the hybrid system software, specifically in the software controlling the boost converter, which could result in thermal stress on transistors and potential system shutdowns [24237, 24637].
Intent (Poor/Accidental Decisions) poor_decisions, accidental_decisions (a) The articles provide information related to poor_decisions contributing to the software failure incident: 1. The software failure incident in the Toyota Prius vehicles was due to a programming error that could cause the gas-electric hybrid systems to shut down. This error was attributed to problems in software settings on the newest Prius generation, which could stress and damage transistors in the hybrid systems [24237, 24637]. 2. The recalls and technical problems faced by Toyota highlighted the risks of relying on electronics in vehicles, which have become more complex with the increasing use of technology and electronic systems. The article mentions that advancements in vehicle technology bring benefits but also pose risks, as seen in the case of Toyota's recalls due to software and electronic issues [498]. (b) The articles provide information related to accidental_decisions contributing to the software failure incident: 1. The software glitch in the Toyota Prius hybrid system was described as a programming error that caused higher thermal stress in certain transistors within the booster converter, leading to deformation or damage. This glitch could result in various warning lights being illuminated and the vehicle entering a failsafe mode, with the hybrid system potentially shutting down in limited cases [24637]. 2. The broader issues faced by Toyota, including problems with accelerators getting trapped under floor mats or becoming stuck, were attributed to conventional mechanical issues. However, Transportation Secretary Ray LaHood mentioned a review to determine if automobile engines could be disrupted by electromagnetic interference, indicating a potential accidental decision contributing to the failures [498].
Capability (Incompetence/Accidental) development_incompetence (a) The software failure incident occurring due to development incompetence: - The software failure incident in the Toyota Prius vehicles was due to a programming error that could cause the gas-electric hybrid systems to shut down. This error was related to problems in software settings on the newest Prius generation, which could stress and damage transistors in the hybrid systems [Article 24237]. - The recall was issued due to a programming glitch in the hybrid system of the third-generation Prius cars, specifically in the software used to control the boost converter. The setting of the software could cause higher thermal stress in certain transistors within the booster converter, leading to various warning lights being illuminated and possibly causing the vehicle to enter a failsafe mode [Article 24637]. (b) The software failure incident occurring accidentally: - The article mentions that the wider problems with accelerators in Toyota's non-hybrid cars could be conventional mechanical issues, such as accelerators getting trapped under floor mats or becoming stuck on their own. This issue was not specifically attributed to intentional actions but rather to mechanical problems [Article 498].
Duration temporary (a) The software failure incident in the articles appears to be temporary. The incident was caused by a programming glitch in the hybrid system software of Toyota Prius vehicles, leading to issues such as warning lights being illuminated, the vehicle entering a failsafe mode, and in limited cases, the hybrid system shutting down, causing the vehicle to stop [24237, 24637]. The problem was specifically identified in the software used to control the boost converter in a module that is part of the hybrid system, resulting in higher thermal stress in certain transistors within the booster converter, leading to deformation or damage of the transistors [24637]. Additionally, the article mentions that Toyota has been proactive in addressing safety concerns since a damaging quality crisis in 2010, indicating that the software failure incident was not a permanent issue but rather a specific problem that needed to be addressed through a recall [24637].
Behaviour crash, omission, value, byzantine, other (a) crash: The software failure incident in the Toyota Prius vehicles caused the hybrid system to shut down, resulting in the loss of power and the vehicle coming to a stop while being driven [24237, 24637]. (b) omission: The software glitch in the Prius could cause the vehicle to enter a failsafe mode with reduced driving power, and in limited cases, the hybrid system could shut down, causing the vehicle to stop [24637]. (c) timing: The software issue in the Prius was related to a time lag when the vehicle switches between its gas engine and the electric motor, potentially causing a delay in switching between the traditional hydraulic brakes and the electronic braking system [498]. (d) value: The software controlling the boost converter in the Prius had a setting that could cause higher thermal stress in certain transistors within the booster converter, leading to warning lights being illuminated and the vehicle entering a failsafe mode [24637]. (e) byzantine: The software glitch in the Prius caused various warning lights to be illuminated and could result in the vehicle entering a failsafe mode, with the hybrid system shutting down in some cases, leading to inconsistent brake feel during slow and steady application of brakes on rough or slick road surfaces [24637, 498]. (f) other: The software failure incident in the Prius also led to problems related to the brake accumulator in a previous recall, indicating a recurring issue with the software in the vehicle [24237].

IoT System Layer

Layer Option Rationale
Perception processing_unit, embedded_software (a) sensor: The software failure incident related to the Prius recall was not directly linked to a sensor error. The issue was with a programming glitch in the hybrid system's software that could cause stress and damage to transistors within the booster converter, leading to warning lights being illuminated and the vehicle entering a failsafe mode [Article 24237, Article 24637]. (b) actuator: The failure was not attributed to an actuator error in the cyber physical system. The recall was due to a programming error in the software controlling the boost converter in the hybrid system, causing thermal stress on transistors and potential system shutdowns [Article 24237, Article 24637]. (c) processing_unit: The software failure incident was directly related to a processing error. Toyota mentioned that the problem was in the software used to control the boost converter in the hybrid system, leading to higher thermal stress in certain transistors and potential system shutdowns [Article 24637]. (d) network_communication: The failure was not associated with a network communication error. The recall was due to a programming glitch in the hybrid system's software, causing issues with transistors and potential system shutdowns, rather than network communication errors [Article 24237, Article 24637]. (e) embedded_software: The software failure incident was primarily caused by an error in the embedded software. Toyota identified a programming glitch in the software controlling the boost converter in the hybrid system as the root cause of the issue, leading to transistors being stressed and potential system shutdowns [Article 24237, Article 24637].
Communication unknown The software failure incident reported in the provided articles does not specifically mention a failure related to the communication layer of the cyber physical system. The incidents described in the articles primarily focus on software glitches and errors within the hybrid systems of Toyota Prius vehicles, leading to issues such as the system shutting down or entering a fail-safe mode while driving. These failures are attributed to programming errors and software settings within the hybrid systems, rather than failures at the communication layer of the cyber physical system. Therefore, the articles do not provide information on failures related to the link_level or connectivity_level of the cyber physical system.
Application TRUE The software failure incident related to the Toyota Prius recall was not explicitly mentioned to be related to the application layer of the cyber physical system. The articles primarily focused on a programming error in the hybrid system software that could cause the hybrid system to shut down, stressing and damaging transistors in the hybrid systems, leading to warning lights and the vehicle entering a fail-safe mode [24237, 24637]. Therefore, it is unknown whether the failure was specifically related to the application layer as defined.

Other Details

Category Option Rationale
Consequence property, delay, non-human, theoretical_consequence (a) death: People lost their lives due to the software failure - There is no mention of any deaths related to the software failure incident in the provided articles. [24237, 24637, 498] (b) harm: People were physically harmed due to the software failure - There is no mention of any physical harm to individuals due to the software failure incident in the provided articles. [24237, 24637, 498] (c) basic: People's access to food or shelter was impacted because of the software failure - There is no mention of people's access to food or shelter being impacted by the software failure incident in the provided articles. [24237, 24637, 498] (d) property: People's material goods, money, or data was impacted due to the software failure - The software failure incident led to the recall of 1.9 million Toyota Prius vehicles worldwide due to a programming error that could cause their gas-electric hybrid systems to shut down. This could potentially impact the owners' use of their vehicles and their convenience. [24237, 24637] (e) delay: People had to postpone an activity due to the software failure - The software failure incident could potentially cause the hybrid system to shut down while the vehicle is being driven, resulting in the loss of power and the vehicle coming to a stop. This could lead to delays for affected drivers. [24237, 24637] (f) non-human: Non-human entities were impacted due to the software failure - The software failure incident affected the functionality of the hybrid systems in Toyota Prius vehicles, leading to a recall of 1.9 million vehicles worldwide. [24237, 24637] (g) no_consequence: There were no real observed consequences of the software failure - The software failure incident resulted in the recall of 1.9 million Toyota Prius vehicles due to a programming error that could cause the hybrid systems to shut down. While no accidents were reported related to the defect, the potential consequences of the software failure led to the recall. [24237, 24637] (h) theoretical_consequence: There were potential consequences discussed of the software failure that did not occur - The articles discuss potential consequences of the software failure incident, such as the hybrid system shutting down while the vehicle is being driven, resulting in the loss of power and the vehicle coming to a stop. However, there is no mention of these potential consequences actually occurring. [24237, 24637] (i) other: Was there consequence(s) of the software failure not described in the (a to h) options? What is the other consequence(s)? - There are no other consequences of the software failure incident mentioned in the provided articles. [24237, 24637, 498]
Domain transportation, other (a) The software failure incident reported in the articles is related to the transportation industry, specifically affecting Toyota Motor Corp's Prius vehicles due to a programming glitch in their hybrid system [24237, 24637]. (m) Additionally, the articles mention that the software failure incident is related to the automotive industry, which is not explicitly listed in the provided options but can be categorized under the "other" category [24237, 24637, 498].

Sources

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