Auto Gurus in the house;

what does this diagnostic code mean and how can it be fixed? car runs smooth and easy but check engine light is on.
any suggestions?

What car is it?

It's either our fuel has fouled your rear oxygen sensor or the the catalyst.
You should also have a panel beater/mechanic check your rear catalyst to confirm it has not disintegrated.

It's a V6?

2003 Toyota corolla 1.8l

How long have you had the code?
Did you buy black market fuel or from a new fuel station, if it's a recent code?

If you've had it for a while and you start noticing the car is burning more fuel, change the rear oxygen sensor

if the catalyst is the problem, how can it be repaired? and the oxygen sensors any implications?

@ niss parts
not black market fuel, the car failed emission test in the states before it came to Nigeria, it has been that way. just that the MIL goes off when reset and resurfaces after a while when rev at higher Rpm

Okay, most people around here, myself inclusive drive around with an 0420 as long as you are sure the catalyst itself is fine and you change your o2 sensors every 60,000 miles

you have not been able to isolate the two culprits, how do you know whether it is the catalyst or the 02 sensor? the scan mentioned only the catalyst the mechanic is suggesting we change the sensors but i don't see the relationship,also he couldn't verify the status of the catalyst though

thanks for your efforts

The oxygen sensor measures the performance of the catalyst based on the car manufacturer's specs for emissions.
So, either the oxygen sensor is faulty, the catalyst itself is faulty, or the oxygen sensor is sensitive to our grade of fuel.

thanks for your response,

the issue of foul petrol is over ruled for now cos it started showing it back in the states, the mech guy in the states said it is a simple stuff and can be fixed anywhere only for me to bring it to Nigeria to Give my mechanic heart attack, all the same i will change both