symone

Hello

Since 1 year i have this error code in my GX 470. I have replace all oxygen sensor but after 1 day the error code is coming back.

Anybody knows how to resolve it ?

chiph9

Check for a loose connector or burnt wire on the O2 sensors. Also check spark plugs, air flow sensor, air cleaner, coil packs, or anything else that could make it run rich.

Read this for more info:

http://www.autoserviceprofessional.c...yota-p0420-dtc

Chip H.

6080prado

Since he is getting both a 420 and 430 code, that indicates bad readings at both cats. It seems highly unlikely, short of running a tank of leaded gas through the engine, that both cats or O2 sensors on each side would fail simultaneously. But certainly possible.

I would agree that it does seem to be something upstream causing a bad fuel mix and it is giving funny readings at both cats. I would suspect it would need to be something common to both sides of the exhaust (unless the exhaust is interconnected, which I don't know if that is the case on a GX). Hopefully not a bad ECU.

RCsGX

What sensors did you actually replace? There's 4 total; 2 on the manifold and 2 pre-cat on each side. The upstream sensor (on the manifolds) is your air / fuel, the downstream sensor (pre-cat) is your O2 sensors.

Also which sensors did you install / have installed? Some come w/ pigtails that you have to splice in to the factory wiring, that's why I'm asking...maybe there's a wiring problem.

symone

I have replace all of 4 ! (2 on the manifold and 2 pre-cat on each side.).
All parts is O/E equipment 2 denso and 2 bosh whitout any factory wiring.
For the story the issue come after coil and spark plug ignition problem. The car has used by my wife during 1 month whit this issue and when I replace all of 8 spark plug and all of 8 ignition coil, the P0420 and P0430 error appear.

ELITech

I am confused here. You had both of these codes for one year?

Or you had them checked one year ago, and they are back again...

symone

I have both of these codes for one year ! I have replace first 2 on the manifold 5 month ago ! No success!
Now i replace 2 on pre catalyst ! The issue still there !

chiph9

Can you post a photo of your sensors, and especially the wiring?

Chip H.

symone

Please check !

http://www.fcpimport.com/products/to...n-sensor-24594


http://www.fcpimport.com/products/le...-cruiser-15101

symone

hello ???
Anybody there ?

lacroix

u need new catalytic converters, most aftermarket cats will throw this code. no other way than to order 2 new manifolds to fix this. sorry

RCsGX

You said you used Denso and Bosch but the one link is for NTK, the other link is for Bosch. Are you sure you used Densos?

If not, use OEM Densos sensors. Our ECUs are picky when it comes to aftermarket O2s. As far as Bosch, a lot of 1st gen Tundra owners (same engine as our GX) have had problems using Bosch O2s because the voltage is different so the check engine light would always come back on. I'm not sure if that's still the case but it was when I owned my Tundra.

lacroix

always install Toyota factory parts, but your problem would not be 02 related and 02 is a input reading on air monitored after cat. replace manifolds, I have change many due to leaking

RCsGX

OP it's your GX do as you want but trust me when I say it could be your O2s. Get Densos. Don't go spending thousands on cats until you try Denso's first.

There are MANY 1st gen Tundra owners that also pulled the same 2 codes as you did; P0430 / P0420 and the codes went away when replacing w/ Denso's. Again, some even had to switch from brand new Bosch to Densos for the codes to go away but they went away and never came back.



Off to the beach for a week long vacation...Siesta Keys here we come!! I hope you get it figured out! Good luck.

6080prado

Don't discount RC's advice regarding aftermarket O2 sensors. People had loads of problems with aftermarket O2 sensors on their Landcruisers as well (80 series, not sure about the 100 series). I'm not sure why Toyotas are so finicky, but they do seem to be.