A fluent answer is not evidence. Freeze the starting facts, make the proposed next test explicit, and let the physical result decide what was useful.
Record year, make, model, engine or powertrain, market, and the evidence available at the starting line. Reject an answer that silently assumes missing vehicle details.
The recommendation should name what to measure or inspect, what outcomes are expected, and how those outcomes separate at least two plausible causes.
A useful assistant distinguishes observations from inferences and asks for high-value evidence before collapsing uncertainty into a parts recommendation.
Look for appropriate cautions and a clear handoff when the job requires vehicle-specific service information, advanced tooling, high-voltage or safety expertise, or a physical inspection.
Keep the original output. Document the real measurement or observation, what the recommendation clarified, and every vague, wrong, or unsafe part of the answer.
MECH AI is decision support. It does not replace official service information, hands-on inspection, a professional scan tool, or a technician. Current public OBD support is read-only for supported functions; vehicle and feature coverage vary.