AUTO / KNOWLEDGE
Worked examples
These examples show how to read an electronic clue without turning it into a definitive diagnosis.
P0420
Catalyst efficiency
The catalyst, oxygen sensors, exhaust leaks or poor combustion may be involved. Replacing the catalyst before checking the rest can be an expensive mistake.
P0300
Random misfire
Spark plugs, coils, intake, fuel or compression may be involved. Stop driving if the engine light flashes or the engine shakes severely.
Red light
Oil pressure
This is not a routine service reminder. It may mean insufficient lubrication pressure: stop safely and switch off the engine.
Recalls
2020 Toyota Corolla
A model search returns general NHTSA campaigns. Confirm the exact VIN on the official portal to know whether one vehicle is included.