P0420 & P0135 Codes

I have been rejected from licensing my vehicle 1999 Mitsubishi Eclipse GSX 2.0L Turbo due to the P0420 & P0135 codes showing up. The "Check Engine" light is and has been on for some time already (1 Year or so).

I had this problem a few years back and the local garage changed the O2 sensor after the catalytic converter and it went away for about 6 months.

I did the same thing this time and was able to successfully drive 8 blocks and park without it going on. When I restarted the vehicle it remained on.

I reset the sensors by disconnecting the battery for a short time.

Could I need a catalytic converter? My exhaust doesn't have that acidic smell like it once did, instead smells like lawn mower exhaust and is showing some carbon around the tailpipe.

Thanks

Check the resistence of the o2 heater circuit. 11 - 16 ohms cold. If not replace your UPSTREAM o2 sensor. For the 0420 use the search feature.

I have a 2001 Tacoma 4DR 4x4, had cat conv replaced, 8 mos later had it done again on the same bank. Had tested showing P0420 again. Toyota said that any movement of cat either way on exhaust could cause light to trip. True? They want me to spend $2800 for a new exhaust system. I can't pass inspection, tried resetting and erasing codes, still won't pass. Any ideas?

Check the O2 heater fuse, check for proper O2 heater voltage supply..
Hopeffully, if the O2 code is resolved maybe but not sure the P0420 would be also cleared, but we have to wait and see.

Keep posted

what kind of cat did you purchase originally? Was it very cheap and how was the installation? Was it professional or just hacked up. All this will make a difference. Yes the cat needs to be installed in the correct location. Also if you use the search feature you'll see that theres alot of problems with recurring 0420 when an inexpensive cat is used.

I had the work done at Meineke. I wasn't cheap, around $300+ for one converter. After the 2nd replacement, the work looks real shotty. Talked to another muffler place about work, they will replace the entire section plus both convertors for around the same price, but with Magna-Flow brand and it will be a solid fit. Hopefully this will work. I am having the State Mechanic of TN look at it next week before I have any work done. He is able to test the O2 sensors also. Thanks for the info. Any more ideas please let me know.
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