Free AI Mechanic

Describe the vehicle before asking for a diagnostic plan

Useful troubleshooting starts with context, not a parts recommendation. Include the year, make, model, mileage, engine size or engine family, fuel type and transmission if known. For a heavy-duty truck, identify the chassis and engine separately: the badge alone does not identify the engine or its service specifications.

• Copy the exact diagnostic trouble codes and which module reported them. For HD equipment, include SPN/FMI, active or inactive status, and occurrence information when available.
• Describe when the symptom occurs: cold start, warm idle, acceleration, braking, under load or after rain. Note whether a warning light is steady or flashing.
• Include recent repairs, battery disconnection, fluid changes and observations. Label measurements with units and test conditions; separate what you measured from what you suspect.
• Ask for ranked possibilities, the evidence that would distinguish them, and which checks need a qualified technician. A code identifies a detected condition, not automatically a failed part.

Example questions for a mechanic or vehicle owner

Check-engine light

“My 2017 Toyota Camry 2.5L has a steady check-engine light and P0171. It idles roughly when warm; no parts have been replaced. What additional freeze-frame data and observations would help separate possible causes before buying parts? Identify what is uncertain.”

Electrical or no-start complaint

“My 2019 Ford F-150 3.5L has an intermittent no-crank condition after sitting overnight. The dash lights come on, but I have not measured battery voltage. What history and safe observations should I collect, and which battery, connection or starter-circuit tests should a technician perform using the correct wiring diagram?”

Heavy-duty truck

“My 2020 Freightliner Cascadia with a Detroit DD15 shows an aftertreatment warning under highway load. I will provide the exact SPN/FMI and active status from the scan tool. What engine identification, recent service history and OEM diagnostic information are needed before recommending a test? Do not assume a forced regeneration is appropriate.”

Verify suggestions before authorizing a repair

This is model-based AI and it can be wrong, omit a cause or confuse vehicle configurations. It cannot inspect a vehicle, verify a measurement or prove a diagnosis. Treat an answer as a starting hypothesis, then compare it with actual tests and the current OEM procedure for the exact vehicle and engine.

Do not accept guessed torque values, fluid capacities, wiring pinouts, brake limits or service intervals. Ask for the source and configuration boundary; if these cannot be verified, use the applicable service information instead. Do not bypass safety systems, work beneath an unsupported vehicle, probe high-voltage systems or attempt fuel-pressure and air-brake work without suitable training and equipment. Stop using a vehicle with a serious brake, overheating or other safety concern and arrange professional assessment.

Turn findings into a shop workflow

Keep the customer complaint, confirmed findings and proposed work separate. Repairius provides estimates, work orders and inspections for professional shops; an AI suggestion does not replace technician findings or customer authorization.

• Diagnostic scanner tool for exploring code-related questions.
• Repair estimate template for organizing a proposed scope.
• Independent-shop estimate and authorization checklist.