Working on my dads 2000 4runner v-6 50,000 miles. Warning light came on after air filter change. Autozone used a meter and said o2 sensor. Bought one replaced it (bosch brand) and warning light came on again. So I cleaned the maf sensor and cleaned old oe o2 sensor and put it back in. Now I can tell its running better for sure, but can you tell me how many miles before the warning light comes on? im tired of riding in circles. 35 miles and counting. Thanks for the help.