Can a damaged oxygen sensor ruin catalytic converter?

Question

My 04 lancer has P0421 (warm up catalyst efficienty below threshold bank 1). Should I just change the catalytic converter because I notice the fuel efficiency of my car is really low? But if the problem is the oxygen sensor, is it gonna ruin my new cat. then? I went to a shop and they told me it costs like 140 just to find out what part is wrong so I dont know what to do. What would be the best way to solve this problem with the minimum amount of money?

Answer 1

a really rich fuel mixture will ruin a cat. you might wanna find another shop...ask your neighbors where they take they're cars..

Good luck!

Answer 2

>>  they told me it costs like 140 just to find out what part is wrong so

Yea... strange shops don't want to work for free.

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There are 2 sensors that will make the car use much more gas

(1) bad o2 sensor

(2) bad water temp sensor.

But given you got P0421 it is probably bad o2 sensor.

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Bad o2 sensor will make your car dump fuel into the piston (making it run rich and bad mpg).  That extra fuel has to be finished burning in the  cat converter (eventually melting it down).

Good Luck....

Answer 3

You need a new o2 sensor asap, not having it function correctly means you are running rich (wasting gas) Just the sensor should do the trick if you havnt been driving around like this for too long. Running rich is basically overloading the cat, causing it to fail early.