Prompt - Used Car Buying Checklist and Questions

Prompt - Car Problem Diagnostic Helper

Act as an experienced mechanic explaining things clearly. My car is [MAKE/MODEL/YEAR] and the symptom is [DESCRIBE: sound, warning light, behavior, when it happens]. Help me narrow it down: the most likely causes ranked by probability, simple checks I can safely do myself, rough repair cost ranges, how urgent it is (can I drive it?), and what to tell a mechanic so I don't get upsold. Note anything that's a safety 'stop driving now' issue.