you should never have to change your oxygen sensors. The only time you have to is if the PCM (powertrain control module) is not recieving any input from them. This would cause an MIL (engine light) to illuminate.
You only need to change it if it has failed. There is no other reason.
The oxygen sensor on a vehicle will need to be changed about every 100,000 miles for the newer vehicles. An older vehicle might need this part to be changed more often. If this part is working properly, there is no need to change it, no matter how many miles are driven.
I believe the manuals will say 100,000 miles, but I only change them when they generate an error. If your check engine light is on, a DLC reader (Which you can "borrow" from most part stores) will show what errors or registered, and the O2 sensor is a common one on older cars.
How often should you change the fuel filter?
The check engine light for the 2001 Isuzu Rodeo often comes on because of a sensor that is damaged or malfunctioning. The most common sensor is an oxygen sensor and when reset, this often allows the light to be reset.
It will require a special socket with a slot down the side so as not to damage the wiring. It may be cheaper to have a shop do it as the sensors do not go bad very often.
Code PO131 typically refers to a diagnostic trouble code (DTC) related to the oxygen sensor circuit in a vehicle, specifically indicating a malfunction in the heater circuit of the oxygen sensor (often the upstream sensor). This code can lead to issues with fuel efficiency and increased emissions if not addressed. It usually prompts a check of the wiring and connections to the oxygen sensor, as well as the sensor itself for proper functionality.
When the computer throws the code that you need to change the sensor.
Every 50k miles
The more use they get the less effective they are, your check engine light will let you know when they need replacement.
Your O2 sensor is a "part that is designed to wear out". there is no standard on replacing them, but if your car is running fine, and your check engine light comes on, and stays on, it's probably an O2 sensor.
A tune up is always appropriate. Make certain that the ignition and injectors are working properly and that the oxygen sensor hasn't worn out. Check with the dealer to find out how often the oxygen sensor should be replaced. Also make sure that the air filter is clean. A tune-up should always include a diagnostic check using a code scanner.