Many people hearing about ISO 26262 for the first time will have the following reactions:
"Just another standard?"
"Is it only understandable by engineers?"
"What does it have to do with me?"
In fact, it can be explained in one sentence: ISO 26262 is essentially about preventing "the car from making its own mistakes and harming people." It is not about preventing you from not knowing how to drive, but rather preventing the system from failing when you have made no mistakes.
I. Let's Speak Plainly: What Is "Functional Safety"?
Let's not talk about ISO 26262 for now. Imagine a real scenario:
You are driving normally on the highway
You are not pressing the accelerator
Suddenly, the vehicle accelerates on its own
Question: Is this a driving issue or a system issue?
The answer is clear: this is a risk caused by system functional failure.
Functional Safety is exactly about solving this kind of problem:
When the system's "function is abnormal",
can harm to people be avoided?
Note two key words:
❌ It is not about whether the performance is good or not
❌ It is not about whether there are many functions or not
✅ It is: whether it remains safe when a fault occurs
II. What Is ISO 26262? The One-Sentence Version
ISO 26262 is the functional safety standard for the automotive industry.
Translated into plain language:
It specifies a complete set of methods
to ensure that the electronic and software systems of a vehicle
even if they fail, will not cause unacceptable safety risks.
It primarily governs:
Electronic systems
Software systems
Electronically controlled mechanical systems
For example:
Braking systems (Brake by Wire)
Steering systems (EPS)
Acceleration systems (Accelerator pedal)
Autonomous driving / ADAS
Battery Management Systems (BMS)
III. Why Is It Specifically the "Automotive" Industry That Needs ISO 26262?
Because modern cars have already become
four wheels + a large electronic system
A typical car usually contains:
70 to 150 ECUs
Over 100 million lines of code
Highly coupled sensors, controllers, and actuators
Here comes the problem:
Software will inevitably have bugs
Electronics will inevitably fail
So if:
A bug occurs in the infotainment system → at most, a black screen
A bug occurs in the braking system → it could cost lives
The emergence of ISO 26262 is to answer this question:
Which errors are acceptable? Which are absolutely not?
IV. What Exactly Does ISO 26262 Do?
I will explain it clearly using a minimalist logical chain
1️⃣ First, ask a question:
"If this function fails, will it hurt people?"
For example:
Rearview camera failure
Sudden lockup of electric power steering
False triggering of automatic emergency braking
The first step of ISO 26262 is called: Hazard Analysis and Risk Assessment (HARA)
The essence is: systematically imagining the "worst-case scenario"
2️⃣ Classify the risks:
Not all problems are equally severe. ISO 26262 uses a level to indicate the severity of the risk:
ASIL: A → D
ASIL A: Low risk
ASIL B / C: Medium risk
ASIL D: Highest risk (fatal)
For example:
Window lift failure → possibly QM (no ASIL required)
Steering failure → almost certainly ASIL D
The higher the level, the stricter the requirements.
3️⃣ From "Thinking It Through" to "Designing It"
Once the risk level is determined, the subsequent tasks become highly engineering-oriented:
Is redundancy needed in the architecture?
Does the software need monitoring?
How to detect when a sensor fails?
What "safe state" should the system enter when an anomaly occurs?
For example:
Braking system failure → degraded but still capable of braking
Steering anomaly → speed limitation + driver alert
ISO 26262 does not care what technology you use; it only cares: have you systematically prevented the risks?
4️⃣ The most critical point:
It is not about "just building it", but "being able to prove that you are safe"
A very "annoying" aspect of ISO 26262 is:
Everything requires evidence
Why was it designed this way?
Why is it considered safe?
Who reviewed it?
Was there independent confirmation?
This is why everyone says:
Functional Safety = Technology + Process + Documentation
V. What Is the Difference Between ISO 26262 and "Quality Standards"?
This is an area where many people get confused.
I will distinguish them in one sentence:
Quality (e.g., IATF 16949)
Prevents "doing it poorly"
Functional Safety (ISO 26262)
Prevents "errors causing fatalities"
Quality focuses on:
Consistency
Stability
Pass rate
Functional safety focuses on:
What happens in extreme situations
Whether it remains safe when errors occur
The two are not substitutes for each other, but operate at different levels.
VI. Why Is Everyone Paying More Attention to ISO 26262 Now?
The reasons are actually very practical:
1️⃣ NEVs & smart vehicles are too "software-defined"
2️⃣ The liability boundaries for autonomous driving are becoming increasingly sensitive
3️⃣ Regulations, customers, and accident investigations are all forcing the issue
To summarize in one sentence:
As "humans" gradually stop directly controlling the vehicle,
the system must take responsibility for safety.
And ISO 26262 is currently the most fundamental and universal functional safety consensus in the global automotive industry.
VII. Final Summary in One Sentence
If you only remember one thing: ISO 26262 is not about making cars smarter, but about preventing cars from "harming people when they make mistakes".
It does not pursue "never making a mistake", but rather pursues: even if a mistake occurs, the consequences are controllable.