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1997 Corolla--may need new computer

Our son’s '97 Corolla engine light will not go off–they have changed 2 O-2 sensors and put in a used computer new to the car and it still is coming on–they now want to put in a new ($1,000 part) computer

Help! How do they know it’s the comuter

You may be able to get your computer repaired for much less. Google Toyoya Corolla ECM repair.

THEY may not know what THEY are doing. There are shops, and dealers, who don’t have a clue. Yours may be one of those. Ask around for a mechanic/shop who is capable in electronics in cars.
The check engine light won’t go off because THEY haven’t fixed the problem.

Are they consistently getting the same codes from the computer? You can have codes stating “EGO (oxygen sensor) indicates engine too lean” or “too rich”, and they don’t necessarily mean that there’s anything wrong with the oxygen sensor, but that the computer can’t correct the lean or rich condition. For example, if you have an exhaust leak, air can be getting in, fooling the sensor into thinking the engine is lean, so the computer dumps more gas in to correct the mixture—the next message you get is that it’s too rich, so the computer leans the mixture—repeat to infinity. There are many other problems that can cause a lean or rich code coming up. Weak fuel pump, bad fuel injectors, bad fuel pressure regulator, vacuum leaks, etc. The sensors may be good and just doing their job–reporting what they see in the exhaust stream–oxygen or lack of it. And the ECM (computer) is typically one of the most reliable parts on any car. Plus you say they put in a used computer and the problem is unchanged. Seems to indicate nothing wrong with the original computer. (and hopefully if they put in a used one, they got one from the same model, year, and engine, since I doubt this shop has the skill to reprogram one)

It sounds like you need a new shop that has some techs with a better skill set–ones that will try to diagnose the problem instead of guessing and throwing parts at it with your money.