2006 DCSB SR5 P0430 & P0420

20 is Bank 1
30 is Bank 2

Time for me to read up on this and learn.

Truck has some frame rot so budget conscious on this rig unlike my other trucks. Just has to make it another 20 years cause my dad is 78 and don’t think will be driving much longer than that. And he has 3 other vehicles too.

 

Essentially it means the catyletic converters are no longer functioning effectively, if they are still working somewhat often you can use an O2 sensor spacer on the rear O2 sensors to keep the codes from setting at least for awhile but once they degrade to a point that they are no longer functioning at all spacers typically won't "fool" it.

To understand why the code is setting you have to understand how the PCM monitors catalyst efficiency and the voltage thresholds for an O2 sensor.
Because a normally functioning converter stores and consumes oxygen this allows the PCM to monitor their function using the AFR and O2 sensor.

There are 2 methods used to monitor the catalytic converter function:

Downstream O2 switch rate: The PCM compares the rich/lean switch rate of the upstream and downstream sensors under certain driving conditions. (older vehicles for the most part used this method and were relatively easy to "fool" with various methods)

Oxygen storage capacity: The PCM will deliberately force the air/fuel ratio to a rich or lean state under certain driving conditions and measure the length of time between when the upstream sensor switches and when the downstream sensor switches. (almost all modern vehicles use this method or a combination of both methods and are harder to "fool")


A standard O2 sensor generates a 0-1v signal based on oxygen in the exhaust, because they have a very narrow operating window essentially anything above 0.5V (500mV) is rich (<14.7:1) and below 0.5V (500mV) is lean (>14.7:1) although usually the "dead zone" threshold for a lean/rich "switch" is around 0.45V (450mV) - 0.55V (550mV)


The way we check converters and sensor operation with a scan tool is graphing the AFR and O2 sensor data.
It's kinda hard to explain what good and bad data looks like as far as sensor operation but typically with a good functioning cat at operating temp the downstream sensor should stay relatively constant at around 0.7V (700mV) when engine speed and load is relatively constant.

 

So most likely bad cats and $1-2k to replace? Maybe do O2 sensors at the same time to start fresh?

 

1 Make sure there are no exhaust leaks
2 gas cap leak can set the po442 po443 (Toyota has updated part)
3 o2 extenders are the best cheap quick get around in most cases for higher mile cats... great cheap try

Note:
New o2 sebsors do the opposite of o2 spacers. Instesd of numbing the reading it now is hyper aware of a lazy cat.

 

yep, most often I’ve seen it pop for exhaust leaks around flanges (not Tacoma, but still)
It doesn’t take much of a leak to throw a code

 

Make sure there are no exhaust leaks but majority of the time P0420/430 is a failed converter.

Like I said if they are still marginal you can probably get by with spacers for awhile.

 

Sounds like spacers are worth a shot, found this thread:

https://www.tacomaworld.com/threads/o2-sensor-spacer-for-p0420-codes.795624/

With this link:
https://jcarpart.com/search?options[unavailable_products]=show&options[prefix]=last&q=o2+spacer

My '02 Tundra had two styles, one with the 2 bolt flange (downstream) and one that went in directly (upstream). I also already have the tool (not here at my dad's but can bring it on the next trip) but my next question is, do I do all 4 sensors (assuming 4) or just the ones reporting or just the downstream?

 

If your doing spacers only put them on the downstream sensors, the idea is to delay the switch rate of the downstream sensors.

 

Original owner had brand new aftermarket converts put on the 150k mile 06 Sienna I bought for a great price. Reason? Well at least part of it. STILL setting Intermittant converter codes... Fix? O2 spacers. 30k + miles ago. No issues.

 

So, two of these?

https://jcarpart.com/products/toyot...-oxygen-spacer-sensor-extension-multi-generic

 

You don't need the bolt flanges, 2nd gens use a standard screw in O2 sensor.

A long spark plug non-fouler like this works if there's enough room.
https://www.oreillyauto.com/detail/c/dorman-help/dorman-help-m18-1-5-steel-non-fouler/mtm0/42109