Diagnostics

Guided decision trees for common car problems. Pick your symptom, answer two or three questions, and get the likely causes with evidence, a drive-or-stop verdict, and what to do next — in about two minutes.

• Check Engine Light — Flashing

  The check engine light is flashing or blinking. What it means — and whether to stop now, drive gently, or tow.

  ~2 min · Includes stop-driving verdicts

• Oil Light — While Driving

  The oil warning light came on while driving. Stop now or keep going? Red vs amber, dipstick branches, and the tow rule.

  ~2 min · Includes stop-driving verdicts

• Battery Light — While Driving

  The battery/charging warning came on while driving. Stop now, drive to safety, or tow? No invented "30–60 minutes" — the decision comes from what else is happening.

  ~2 min · Includes stop-driving verdicts

• Car Smells Like Gas

  A gasoline smell — in the cabin, at the filler, after refueling. Tow, stop, inspect, or monitor? One rule governs it: treat it as a fuel leak until proven otherwise.

  ~2 min · Includes stop-driving verdicts

• Steering Wheel Hard to Turn

  Steering suddenly heavy at speed, gradually heavier, or intermittent. The at-speed emergency procedure, then the hydraulic-vs-electric router.

  ~2 min · Includes stop-driving verdicts

• Car Won’t Shift Into Gear

  Shifter locked in Park, selector moves but the car won’t engage, or a manual won’t take a gear. Routed by what your owner’s manual documents — override, park release, or tow.

  ~2 min · Includes stop-driving verdicts

• Car Stalls When Coming to a Stop

  The engine dies as you slow down, stop, or shift into gear. Route it by when it died and what the restart did — safety gate first, no guesses.

  ~2 min

• TPMS Light On

  The tire-pressure warning is on. Visible damage first, then what the light did, then a gauge check against your door placard — no invented safe mileage, speed, or PSI.

  ~2 min · Includes stop-driving verdicts

• Car Won’t Start

  Clicking, silence, cranking but not firing, or dead after sitting. Two questions to a verdict.

  ~2 min

• Brake Noise — Squeal to Grinding

  Squealing, squeaking, or grinding when you brake. Is it a wear warning — or metal on metal?

  ~2 min · Includes stop-driving verdicts

• Brake Pedal Goes to the Floor

  The pedal sinks too far or feels wrong. With a warning light or visible fluid: this is urgent.

  ~2 min · Includes stop-driving verdicts

• ABS Warning Light

  The ABS light is on. What it means — and when it comes with the red brake light, stop.

  ~2 min · Includes stop-driving verdicts

• Coolant Leak

  Visible leak, running hot, or coolant missing with no puddle. Overheating logic is strict here.

  ~2 min · Includes stop-driving verdicts

• Exhaust Smell Inside Car

  Burned exhaust fumes inside the cabin. Symptoms first, raw fuel vs burned fumes, then what your owner’s manual says — some say do not drive, others windows fully open to an inspection.

  ~2 min · Includes stop-driving verdicts

• Airbag Light On

  The airbag or SRS light stayed on, flashes, or never appeared at startup. Read the lamp pattern, check your VIN for an open NHTSA recall, then decide.

  ~2 min · Includes stop-driving verdicts

• Clicking Noise When Turning

  Clicking or ticking that follows your steering. Road speed vs engine speed, one side vs both — and the loud-click rule.

  ~2 min · Includes stop-driving verdicts

• Windshield Wipers Not Working

  One wiper or both — or wipers that won’t stop. The decision comes from what you can actually see, not the forecast.

  ~2 min · Includes stop-driving verdicts

General guidance for common problems — not a substitute for a qualified inspection. A diagnosis is only confirmed by testing.