8: When the dashboard warning light illuminates, replace the oxygen sensors.
By monitoring the amount of oxygen remaining in the exhaust, oxygen sensors measure the efficiency of combustion. The problem is that they degrade over time, causing an increase in fuel mileage of up to 15%. You will be charged a diagnostic fee when one of them fails, due to the computer lighting up the “service engine soon” light. You should not let your car’s check engine light go out.
An oxygen sensor needs to be replaced every 96,000km on pre-1996 models to keep your mileage high. Sensors should be replaced every 160,000km in 1996 and newer models. Prices for oxygen sensors range from around $65 to over $300. It is possible for some cars to have as many as four sensors, but they rarely fail.