LX 470 PO420 (1 Viewer)

[Lexdawg]

Hello,
My 05 LX 470, 151k miles gave me a CEL and VSC Off yesterday with a PO420 code. Today the CEL is off! It's been real cold here in GA lately and the cars is only taken on short trips daily. Any ideas?? Thanks!

 

[smoltz]

That's a catalyst efficiency code so most likely would be either one of your cats is going or downstream o2 sensor. Which bank was it? If this is the first time this has happened, I would wait to see if it comes back on. If it does and it's the same side, swap your downstream left/right O2 sensors. If the code follows the sensor, replace the sensor, if it stays on the same side then your cat is going and you'll have to explore your options in that realm.

edit: There are a bunch of posts on here too about similar issues so search is also your friend.

 

[Import Driver]

My 06 with around 225k recently had the P0430 code “Catalyst System Efficiency Below Threshold (Bank 2)”. Bank 2 is the right side so I replaced the downstream O2 sensor. That was a couple thousand miles ago and the code has not returned.

If it had returned or if it does return I will consider (as an experiment) trying an J pipe O2 spacer such as this one: Vibrant Performance 19019 Vibrant Performance J-Style Oxygen Sensor Fittings | Summit Racing - https://www.summitracing.com/parts/vpe-19019

 

[Lexdawg]

That's a catalyst efficiency code so most likely would be either one of your cats is going or downstream o2 sensor. Which bank was it? If this is the first time this has happened, I would wait to see if it comes back on. If it does and it's the same side, swap your downstream left/right O2 sensors. If the code follows the sensor, replace the sensor, if it stays on the same side then your cat is going and you'll have to explore your options in that realm.

edit: There are a bunch of posts on here too about similar issues so search is also your friend.

it was bank 1

 

[2001LC]

Short daily drives and or prolong idling, are two of worst things for CAT. CAT works best, when driving on the HWY.

I'd try a high RPM run, to cook-off residue from CAT and o2's.:
Make sure good oil in engine, clean air filter and no vacuum leaks. The dive in lower gear, to hold a stead 4,500 RPM for ~3 minutes. Shift back into D (normal) for 5 minutes drive, to cool down. Then drive at 4,500 RPM again, for 7 minutes. Cold down and next high RPM drive for ~12 minutes. Clear codes see if they come back.