Check engine light

Check Engine light for my 2000 Ford Contour, V6, 90K miles, came on. My technician initially cleaned the throttle body. Light stayed off for a day or so, then came on again. In the end, replaced catalytic converters for BOTH cylinder banks, plus their respective sensors - a major parts and labor expense! Worked for two weeks. Then, Check Engine light came on/stayed on again for a day; went off for a day; came on once again, and has stayed on for two days. Any thoughts? Desperate at this point.

Has anyone read the codes at any point, and bothered to tell you exactly what they were? It seems like the most common response to a check engine light is to throw parts at the problem, when very often that’s not what the car needs.

You need to get the codes read and post them here, it’s impossible to begin diagnosing anything without them.

That CEL (check engine light) is just a kid in class waving her hand trying to get you attention because she has the answer. You need to have the codes read. Some places will read them for FREE. Try Autozone or Advanced Auto Parts. Get the exact code (like P0123) not just their translation into English and post it back here. 

It sounds like your tech is just guessing when there is no excuse in doing that.

Thanks for your assistance. The code is PO420. As originally noted, my tech started with the least invasive and least expensive fix - intake throttle plenum. Then did one bank [sensor + catalytic converter]. Worked for only a couple days. Then replaced the other [the rearmost] bank. Tech is honest, competent, and a first-rate diagnostician. Found a web blog addressing someone else’s similar problem, which respondent concluded that with close to 100k miles it just might be the cat converter. Also mentioned a “precat”. Is there another, primary cat converter farther aft in the exhaust system? Also found a Ford tech service tip which suggests possible causes could include: malfunctioning ECT/CHT; high fuel pressure; damaged exhaust manifold; cylinder misfiring; HO@S wiring concerns; damaged exhaust system pip; damaged muffle/tailpipe assembly; and retarded spark timing. Have not used leaded fuel, nor is there any oil consumption.
Will be taking car back in soon, and will keep you apprised of outcome. Will give tech the Ford service tips page. Any other observations to pass on would be appreciated. Thanks again.