Incident: Toyota Hybrid Recall: Software Failure Leads to Loss of Power

Published Date: 2018-10-05

Postmortem Analysis
Timeline 1. The software failure incident with Toyota's hybrids occurred in October 2008 - November 2014 [77003].
System 1. Hybrid system software in Toyota Prius and Auris hybrids (2010-2014 Prius and 2012-2014 Prius V) [77003].
Responsible Organization 1. Toyota - Toyota was responsible for causing the software failure incident in the recalled Prius and Auris hybrids due to a fault in the hybrid system software [77003].
Impacted Organization 1. Customers who own the affected Toyota Prius and Auris hybrids were impacted by the software failure incident [77003].
Software Causes 1. The software cause of the failure incident in the Toyota recall was related to a fault in the hybrid system software that prevented the vehicles from defaulting to a "failsafe" driving mode, leading to potential loss of power and stalling instead of entering "limp" mode [77003].
Non-software Causes 1. The issue of the vehicles losing power and stalling instead of going into "limp" mode was a non-software cause of the failure incident in the Toyota recall [77003].
Impacts 1. The software failure in Toyota's Prius and Auris hybrids led to a loss of power and stalling instead of activating the "limp" mode as intended, increasing the risk of a crash if the failure occurred at a critical moment [77003].
Preventions 1. Implementing more thorough testing procedures during the initial development phase to catch the software fault before it reaches production [77003]. 2. Conducting comprehensive risk assessments to identify potential failure scenarios and ensuring failsafe mechanisms are robustly tested and implemented [77003]. 3. Enhancing the software update process to ensure that all previous issues and potential future scenarios are considered and addressed in a proactive manner [77003].
Fixes 1. Dealership technicians will apply a software patch to the recalled vehicles to fix the software failure incident [77003].
References 1. Toyota's official release [77003]

Software Taxonomy of Faults

Category Option Rationale
Recurring one_organization (a) In the case of Toyota's latest recall for 2.4 million Prius and Auris hybrids, the software failure incident related to the vehicles losing power and stalling instead of going into "limp" mode had happened before within the same organization. The article mentions that this issue was also addressed in two prior recalls from 2014 and 2015, indicating that a similar incident had occurred previously with Toyota's products [77003]. (b) The software failure incident related to the vehicles losing power and stalling instead of going into "limp" mode in the recalled Toyota vehicles does not mention similar incidents happening at other organizations or with their products and services.
Phase (Design/Operation) design, operation (a) The software failure incident in the Toyota recall article can be attributed to the design phase. The issue with the hybrid system software causing the vehicles to lose power and stall instead of going into "limp" mode was a result of a fault in the design of the software. This design flaw led to the failure to activate the failsafe driving mode as intended, increasing the risk of a crash [77003]. (b) The software failure incident can also be linked to the operation phase. While the root cause was a design flaw in the software, the failure manifested during the operation of the vehicles. The article mentions that when a fault is discovered in the hybrid system during operation, the cars should default to a failsafe driving mode. However, in the recalled vehicles, they might lose power and stall instead of going into "limp" mode, which could lead to a crash during operation [77003].
Boundary (Internal/External) within_system (a) The software failure incident related to the Toyota recall is within_system. The issue with the hybrid vehicles losing power and stalling instead of going into "limp" mode is a result of a fault in the vehicles' software. The software should have enabled the cars to default to a failsafe driving mode, but instead, they were not functioning as intended, leading to the increased risk of a crash [77003]. The solution to this issue involves applying a software patch to the recalled vehicles, indicating that the problem lies within the system and can be addressed through software modifications.
Nature (Human/Non-human) non-human_actions (a) The software failure incident in the Toyota recall was due to non-human actions. The issue stemmed from the vehicles' software, where a fault in the hybrid system should have triggered a "failsafe" driving mode but instead caused the vehicles to lose power and stall, increasing the risk of a crash [77003]. (b) The software failure incident was not attributed to human actions in the articles provided.
Dimension (Hardware/Software) software (a) The software failure incident in the Toyota recall article is not due to hardware issues but rather a software issue. The article specifically mentions that the issue stems from the vehicles' software, where the cars might lose power and stall instead of going into "limp" mode as intended. The fix for the problem involves applying a software patch to the recalled vehicles, indicating that the root cause of the failure lies in the software itself [77003].
Objective (Malicious/Non-malicious) non-malicious (a) The software failure incident related to the Toyota recall is non-malicious. The issue with the software in the recalled vehicles is not due to any malicious intent but rather a technical fault that causes the vehicles to lose power and stall instead of going into a failsafe driving mode. This failure poses a risk of a crash but is not a result of any deliberate harm introduced by humans [77003].
Intent (Poor/Accidental Decisions) accidental_decisions (a) The software failure incident related to the Toyota recall was not explicitly linked to poor decisions. The issue stemmed from a fault in the hybrid system software that prevented the vehicles from entering a failsafe driving mode as intended, increasing the risk of a crash [77003]. (b) The software failure incident was more aligned with accidental decisions or mistakes rather than poor decisions. The problem was related to a software glitch that caused the vehicles to lose power and stall instead of entering a failsafe driving mode, which was not the intended behavior. Toyota addressed this issue through a software patch to ensure the proper activation of the failsafe mode [77003].
Capability (Incompetence/Accidental) accidental (a) The software failure incident in the Toyota recall was not explicitly attributed to development incompetence. The issue with the hybrid system software causing the vehicles to lose power and stall instead of entering "limp" mode was identified as a fault that needed to be fixed through a software patch. The article does not mention any incompetence on the part of the development team or organization as the cause of the software failure [77003]. (b) The software failure incident in the Toyota recall was accidental in nature. The issue with the hybrid system software causing the vehicles to lose power and stall instead of entering "limp" mode was not intentional but rather an unintended consequence of the software design. Toyota addressed this issue through a recall and software patch to rectify the accidental failure [77003].
Duration temporary The software failure incident related to the Toyota recall for 2.4 million Prius and Auris hybrids is temporary. The issue with the software in the vehicles caused them to lose power and stall instead of going into "limp" mode as intended, increasing the risk of a crash. This issue was not a permanent failure but rather a temporary one that could be addressed through a software patch applied by dealership technicians [77003].
Behaviour crash, omission, value, other (a) crash: The software failure incident in the Toyota vehicles resulted in the cars losing power and stalling instead of going into a "limp" mode as intended. This loss of power could potentially lead to a crash if it happens at an inopportune moment [77003]. (b) omission: The software issue in the recalled vehicles caused them to omit the expected behavior of defaulting to a "failsafe" driving mode (limp mode) when a fault was detected in the hybrid system. Instead of entering limp mode, the vehicles lost power and stalled, omitting the necessary action to ensure safe driving [77003]. (c) timing: The timing aspect is not explicitly mentioned in the article. (d) value: The software failure incident led to the system performing its intended function incorrectly. Instead of activating the "limp" mode to allow the vehicle to safely get off the road, the software issue caused the vehicles to lose power and stall, which could increase the risk of a crash [77003]. (e) byzantine: The byzantine behavior is not described in the article. (f) other: The software failure incident could be categorized as a failure due to the system not behaving as expected in a critical situation. The software did not respond appropriately to a fault in the hybrid system, leading to a potentially dangerous situation where the vehicles could stall unexpectedly, posing a safety risk [77003].

IoT System Layer

Layer Option Rationale
Perception embedded_software (a) sensor: The software failure incident in the Toyota recall article is related to the embedded software in the vehicles' hybrid system. The issue causes the vehicles to lose power and stall instead of going into a "limp" mode when a fault is discovered in the hybrid system. This failure is not directly related to a sensor error but rather to the software's inability to activate the failsafe driving mode correctly, which is controlled by the embedded software. [77003]
Communication unknown The software failure incident reported in Article 77003 was not related to the communication layer of the cyber physical system. The issue stemmed from the vehicles' software itself, specifically in the hybrid system, where a fault caused the cars to lose power and stall instead of going into a failsafe driving mode. The fix for this issue involved applying a software patch to the recalled vehicles, indicating that the problem was within the software logic and not at the communication layer of the system.
Application TRUE The software failure incident reported in Article #77003 was related to the application layer of the cyber physical system. The issue stemmed from the vehicles' software, specifically in the hybrid system. The fault in the software caused the vehicles to not default to a "failsafe" driving mode as intended, leading to a loss of power and potential stalling instead of entering the safe mode. This failure due to the software issue aligns with the definition of an application layer failure, which involves contributing factors introduced by bugs, operating system errors, unhandled exceptions, and incorrect usage [77003].

Other Details

Category Option Rationale
Consequence property, theoretical_consequence The consequence of the software failure incident related to the Toyota recall mentioned in Article 77003 is as follows: (d) property: People's material goods, money, or data was impacted due to the software failure. The software failure in the Toyota hybrids could lead to a loss of power and stalling instead of activating the "limp" mode as intended. This issue could increase the risk of a crash, potentially impacting the property of the vehicle owners if an accident occurs [77003].
Domain transportation (a) The software failure incident reported in Article 77003 is related to the transportation industry. Toyota issued a recall for 2.4 million Prius and Auris hybrids worldwide due to a software issue in the hybrid system that could cause the vehicles to lose power and stall instead of going into a failsafe driving mode, potentially increasing the risk of a crash [77003].

Sources

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