“Replacing parts until the fault disappears” is not diagnostics.
That’s gambling.
Modern vehicles don’t respond to hope.
They respond to correct test procedures.
Before replacing anything, ask:
• What should this component be doing?
• How do I prove it isn’t?
• What test result would confirm failure?
If you can’t answer those three questions, you’re not diagnosing yet.
Question:
What’s the most expensive “parts dart” you’ve ever seen thrown?