26/12/2025
Plugging in a scan tool and pulling fault codes is not diagnosing a problem — it’s identifying a direction to investigate.
A fault code tells you what the system noticed, not why it happened.
For example:
A code may say “Oxygen sensor fault”
That doesn’t automatically mean the sensor is bad.
It could be a wiring issue, exhaust leak, vacuum leak, fuel problem, or even another component causing incorrect readings.
Real diagnosis requires:
Understanding how the system works
Checking live data, not just stored codes
Testing components and circuits
Verifying power, ground, signal, and mechanical condition
Replacing parts based solely on codes leads to:
Wasted money
Repeat failures
Misdiagnosed vehicles
Bottom line:
Fault codes help narrow the search — they don’t solve the problem.
Proper testing and reasoning do.
Scan tools find clues.
Technicians find causes
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