PO430 Please Help

I parked my truck today as the check engine light turned on. Scanned it and thats the code that came up... PO430 Cat Below Threshold Bank 2

Any advice on what is most common fix?

 

There is an exhaust leak.
An oxygen sensor is not reading (functioning) properly.
The catalytic converter is no longer functioning properly.

Check the above in order from most likely ( cheapest ) to least likely ( expensive ).

 

I was thinking the O2 sensors but how can I check those just pull it out? I do not have a scanner to see O2 activity.

 

Sub'd

 

Is there a way to check the o2 sensor with a meter to see if it's still within spec?

 

I checked O2 sensors with a scan tool at work both S2's are bad so I am replacing all 4 as the truck is at 222,279 miles.

 

In order to check the O2 Sensor correctly you need live data with a scanner tool or software.

 

Sensors don't usually go bad unless you see physical damage. Do as others have instructed. Plus check vacuum leaks, fuel leaks, even low fuel.

I'm pretty sure I finally pin pointed my code. I'm getting 5 gallons per hour.

 

My 05 with a little less miles than you had a bad head gasket, which blew out the material in the cat, and threw the same error code as you. i would check your engine out to see if your cats are blown out, and go from there to see if your head gasket's are OK.

 

The O2 sensors are bad I checked them at work yesterday and they don't read at all. The post cat ones but I think I'm going to replace all 4 O2's because my mileage

 

O2 Sensors are working fine now! I sprayed them with water to clean off the dirt and no more code! Driven about 45 miles so far and code has not come back.

 

You'll have to give it some time.
O2 sensors don't fail hard; I went thru a huge icy puddle (07 highlander) and the code was thrown immediately; check engine on. Drove for a while and the post-cat O2 must have dried out and check engine off; 2 weeks later back on; next day, check engine off. Finally had dealer check it ( CE stayed lit). Replaced post-cat O2 and problem solved.
Post-cat O2s get the most punishment with water, maybe stone strike if your unlucky, etc. Dealer will try to sell you a CAT which is likely BS. Also if you bust a head gasket the antifreeze will damage the sensors, but maybe not the cat.
Good luck.

 

Going on 70 miles now no light and all systems are ready and O2's are reading properly

 

I had a P0420 (the other o2 sensor). My catalytic converter was bad. It was under warranty, so meh.

 

So far so good about 120 miles of driving now and no check engine.

 

Good job, that is nice, never would have think to clean them with water.

 

Thanks! Yeah just clean off the dirt on outside of the O2 sensor. The sensor reads the exhaust and compares it to the ambient temp but if it is covered in dirt then it can not read ambient.

 

So you took the sensors off? Or just cleaned the outside of them? I have the same code and doubt it's the cat. 195k miles

 

I just sprayed water on the outside of them without removing to remove dirt from the tops of them. Still running with no codes 1,500 miles later.