Sensors

I have a 2001 Sentra - back in 2007 the head gasket needed to be replaced along with the theromosat & radiator - needless to say the repairs total near $2,000. However, the sensors were fine then but now the “Check Engine Light:” is always on and 4 sensors need to be replaced. Estimate: $240/each with labor

totalling $1,000. If I let this go the Catalyltic converter will eventually need to be replaced also. (which working fine now)

Does this sound correct? Should I sell the car?

Help and thanks!

You need a mechanic/shop who can troubleshoot a problem; not one who is, only, proficient at changing parts. Ask around.
Let us see the trouble codes.

How do you know that the sensors are at fault? It seems likely that something is wrong and four of your sensors are trying to tell you so.

Tell us what the OBD-II codes are. How many miles are on the car? You might also try another shop or two to see what they think.