P0420 P0430

P0420 and p0430 code keeps showing up, even after I have replaced both catalytic converters, ignition coil, plugs, mass airflow sensor, and O2 sensors, and used fuel cleaner. I can't find any vacuum leaks. Tacoma 2005 With miss at 2,500 RPMs

 

What do your O2 readings and Fuel trims look like? Do some further diagnostics. Get your fuel pressure checked.

 

An OBD reader and associated phone app will help



https://play.google.com/store/apps/details?id=org.prowl.torque&hl=en_US
https://torque-bhp.com/

vgate OBD2 Scanner iCar2 Bluetooth Diagnostic Tool Support All OBD Protocals for Android Devices

https://www.amazon.com/gp/product/B075R62FTH/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

 

I once had this issue right after a dealer replaced my clutch. They told me I needed new cats. I said what I drop it off for a clutch and then the cats magically fail....
After 2 weeks of trouble shooting I found out that the O2 wire harness that runs over the transmission was put on backwards...
In all your work did you remove this harness??

 

LOL my buddy did that after replacing his clutch. Yep from what I've seen these codes rarely mean that the cats are actually bad. A quick reading on an OBD app can generally get you on the right path.

 

The misfire is allowing raw/unburned fuel to reach the converters. Converters do not like raw fuel. Fix the misfire(s) and replace the cats again

 

Lean conditions can cause misfires. Both banks throwing the code means you need to look at things that effect both sides of the engine, injectors are probably out of the picture.
http://www.autotap.com/techlibrary/diagnosing_misfires.asp

 

If he had a mis-fire and no repeat cat failure, he can throw parts at it all he wants until the misfire is gone.

If he is getting tired of replacing expensive cats I recommend finding the cause of the misfire (lack of spark, lack of compression, lack of fuel, whatever) first.

 

Yep he's already thrown too many parts at it. A simple bit of diagnostics with inexpensive tools would have kept him from doing that.

 

I now have those same codes with my 2005 Tacoma V6. I have had it 8 days, the codes just popped up today. My old Actron 9135 will not connect to the 2005. I had to take it to Advance Auto to read the codes. The frame was replaced on this truck. Is looks great underneath, new brake lines, etc. From what I have just read in this thread, I am hoping the problem is what BreadBox mentioned above.

I now have two questions

1) How quickly would the codes pop back up if the dealer cleared them before selling it to me with no codes?

2) I have read some on scanner applications for computers and smart phones. Seems to me that might be the way to go. Any suggestions on what to to get.

Thanks for your insight..

 

When this happened to me it took 1 trip to trigger the light.
Probably 1st trip == pending
Second trip made it light.

I just use a handheld unit from pepboys to troubleshoot this issue.

The telltale sign is the harness is wired short on one O2 and long on the other.
To miss wire this they can't tie down the harness right on top of the transmission.

 

I have a 2005 Tacoma with 4.0L V6. Approaching 200K miles, CEL comes on, goes off after awhile. P0430 Code. Attached are some screen shots from the scan tool. I am replacing the O2 sensors as they have never been replaced before. I'm keeping the truck, figured its good measure. Hoping someone here knows how to read the fuel trim data and give me some direction. Light is out right now. Before buying CATS, I'd rather PAY once and get it right, not shot gun it.
Also, is bank two on the 4.0L V6 the driver's side?
Thanks! Marty