Looking for a little help from someone who has maybe gone through this. My beloved TL kicked the P0420 code this morning. OBDII shows no other codes. I actually just did a scan two days ago with no codes coming from that run.
Anyway, the car has 282,000 miles and I have been looking at a replacement car over the past year or two.....but she just keeps running. Bottom line is that I don't want to drop $1000 for a new cat. Wondering if O2 sensor replacement might be a cheaper attempt to keep her running (although I understand that if it is the sensors it should kick other codes). I did alot of reading of other threads but I admit this is beyond my limited understanding of engine details.

Is trying some new O2 sensors worth the cost (i.e....might it do something), and if so, can someone recommend a reasonably priced brand. I understand that there are a total of 4 sensors?

Any help or recommendations would be appreciated. Thanks

 

Are you experiencing any other symptoms besides just the code?

 

Not really. The only thing that I thought I experienced was a jerk or surge on the highway going about 70. Only happened once last week. That is why I threw the OBDII on it.

 

With almost 300k on the clock I would suspect cat might be about done. You will never know unless you test it.

Bluetooth OBDII scanners - the ones you connect to your phone - should be able to get O2 sensor data. If you find how to graph those values then it will be even easier.

You can get IR thermometer for ~$26:
https://www.harborfreight.com/121-in...ter-63985.html
There's a code for 20% off available right now.

Temp after the cat should be higher if cat is working fine. You want to get closer with the thermometer than this guy, as it reads temp from the area around the pointer, not exactly where the red dot is.

Compare bank 1 and bank 2 - if one is working good you will see the difference, or compare with some other good working car.

 

if you get the 02 sensor, goes with Denso on Rockauto they work greats for the fraction of the OEM price.

 

Have you tried seafoam or any other cleaner type product? It might clear out a slightly clogged cat. You can always go with High flow aftermarket cats or Pre-cat deletes too at a fraction of the price of the OEM cat.

also NTD is NGK, same company when looking at O2 sensors! I installed a denso ones in my 3G TL and the car has been running great! Be sure to google for a rockauto coupon and save some extra $$$.

 

I ran my OBDII for the O2 sensors and the cat seems to be performing properly. I then checked the vac lines and one seemed to have a small hole. Repaired the line and cleared the codes. Today's drive to work (about 50 miles) was trouble free and no codes. Hope that was the issue. Trying to get the car to 300,000. Thanks for all of the suggestions.

 

Nice! glad you've seem to got it sorted