Diagnostics

A P0442 code means a small leak in your evaporative emissions system. Learn how the EVAP system works, the causes ranked by probability, step-by-step diagnosis, and repair costs.

The oil pressure warning light demands instant action: pull over and shut the engine off. Learn the causes ranked by probability, what flickering vs solid means, and repair costs.

A battery warning light signals a charging system fault, not necessarily a bad battery. Learn how to tell alternator failure from battery failure with simple multimeter tests, plus costs and safe next steps.

A solid TPMS light means low tire pressure; a flashing one means the system itself has a fault. Learn how TPMS works, what to do, how to reset the light, and common sensor problems.

An ABS warning light means your anti-lock brakes may be offline while normal braking still works. Learn the most common causes, the critical difference from the red brake light, and safe next steps.

A P0171 code means Bank 1 is running too lean. Learn how fuel trims reveal the cause in minutes, the most likely culprits ranked, and a step-by-step diagnostic process.

A P0420 code doesn’t always mean you need a new catalytic converter. Learn the real causes ranked by probability, how to diagnose them in order, and what repairs actually cost.

A P0300 code means random misfires across multiple cylinders. Learn the causes ranked by probability, a step-by-step diagnostic process, repair costs, and when driving becomes risky.

Reading your car’s error codes takes ten minutes and a $25 tool. Learn how to find the OBD-II port, pull codes, decode P/B/C/U numbers, use live data, and avoid beginner mistakes.

A check engine light can mean anything from a loose gas cap to a failing catalytic converter. Learn what solid vs flashing lights signal, the most common causes, and exactly what to do next.