OBD Code P0420 2001 Corolla?

Question

Hi My check engine light came on the other day,I re-set the computer,came on again today.So I went to Autozone to have it checked for codes.They brought up a code P0420.It says Catalyst is low efficiency bank 1. They gave me a list of things that could've caused the cat to go bad.I'm sure the cat is bad.The list is as follows:

1.catalytic converter defective,failure possibly due to #2,#3,or #4.

2.Engine Misfire or running condition

3.Large vacuum leak

4.Engine oil leakage into exhaust valve guide seals/piston rings.

The car runs very good,good pickup and everthing.No drivability problems.It does use a quart to a quart and a half of oil between oil changes lately.So,I'm thinking cat has failed due to #4.The toyota garage said it would probably cost $2000 or more to have the valve seals and/or piston rings replaced and to install a new cat.The service advisor said I would probably better off trading the car in for a new one.So I went for a second opinion somewhere else that works on toyotas,a reputable chevy dealer, and I have an appointment to have it actually looked at physicaly and diagnosed to see exactly what it is I need to do to correct this.I think the toyota garage is trying to sell me a car,so I went to the chevy dealer,since a chevy/geo prizm is the same exact car with the same exact motor.What do you think it is before they tell me I need a new car too?

Answer 1

I've had the P0420 error code also. Here are the normal problems:

1) Mass Air Flow sensor is bad, easy to fix yourself, costs about $100

2) Front Oxygen Sensor once again not a real hard fix, about $80

3) If it isn't either of the first two then it is most likely your catalytic converter.

I would definitely give those a try before you go and do anything with the seals/piston rings. Might end up saving yourself a couple thousand dollars.