Builds Homer's 2003 GX470 Build (3 Viewers)

[HomersCanyonero]

I ended up sticking the new rear diff breather at the gas cap. It was the easiest path for me.

i considered other options like the bottle jack storage area and the front diff stock location, but in the end the gas cap was staring me in the eye!

 

[Rednexus]

I used the gas cap location too. You can actually get by without the Toyota threaded barb. I pried the cap off the OEM axle breather and put a piece of hose over it and clamped it really tight. It has not come off yet.

 

[HomersCanyonero]

@Rednexus your method might still require you to check the existing diff breather is not restricted or clogged with gunk. Maybe the probability of that is low, but in my case it was fairly easy to remove the existing rear diff breather and replace it with the Toyota oem union. And the nipple on the union is like 3x longer than the stock oem breather.

 

[Rednexus]

@Rednexus your method might still require you to check the existing diff breather is not restricted or clogged with gunk. Maybe the probability of that is low, but in my case it was fairly easy to remove the existing rear diff breather and replace it with the Toyota oem union. And the nipple on the union is like 3x longer than the stock oem breather.

I did the relocate during the December shipping craziness and had no confidence that it would come in before January . It's still holding good after a month or so of driving and off-roading (I gave it a ton of extra hose to account for axle droop) but I do plan to upgrade to the Toyota barbed fitting the next time I change the rear diff fluid. When the cap was pulled off there was a large open hole into the diff, so it wasn't clogged.

 

[HomersCanyonero]

Just documenting the part numbers for the integrated upper catalytic converters left and right. I’m gonna need this soon.

The part numbers for the 2003-2004 appear to be different parts than the 2006-2009. Not sure about 2005s.

These are for 2003-2004 at various sites:

 

[HomersCanyonero]

Replaced the upstream O2 sensors in both banks with Denso ones ordered from RockAuto.

Cleared the codes and went to the gas station to fill up. P0420 and P0430 Codes came back when I pulled into my driveway after 6 mile ride. Arghhh.

The downstream Denso O2 sensors are 3 years old and 35k miles. I’m close to 164k miles.

Smog check due in April 2021 at a STAR facility nonetheless.

i don’t want to do the anti-foulers. I might have to cry when I order the cats.

 

[Brake Weight]

0420 and 0430 are downsteam sensors. I know they're fairly young sensors but could be suspect or possibly the wiring junction back to the bigger harness. If you're feeling froggy enough you can unbolt the header leading to one of the cats and have a look inside to see what it looks like.

 

[HomersCanyonero]

My Bluetooth ODB2 scanner doesn’t tell me which sensor. It just says P0420 Bank 1 and P0430 Bank 2.

Sensor 1 is upstream and sensor 2 is downstream.

I need to find a scanner that tells me which sensor to be sure, but replacing the sensors is a good idea for me if I’m going to go with new cats at some point. I’ll look into replacing the downstream sensors again.

I’m using two apps on my iPhone called Car Scanner and Auto Doctor. Neither says which sensor.

Finally, I spoke with a smog check specialist who gave me a list of California approved aftermarket cats. I need to price those.

Oh and I did a quick video on how to access the upstream O2 sensors
GX470 Upstream O2 Sensor Replacement

 

[Brake Weight]

P0420 Catalyst System Efficiency Below Threshold

How to diagnose, repair, and info on symptoms and causes of a P0420 engine code which means the catalytic converter is no longer performing at a normal level.

www.obd-codes.com

OBD-II Trouble Code: P0430 Catalyst Efficiency Below Threshold (Bank 2)

 

[Rednexus]

0420 and 0430 are downsteam sensors. I know they're fairly young sensors but could be suspect or possibly the wiring junction back to the bigger harness. If you're feeling froggy enough you can unbolt the header leading to one of the cats and have a look inside to see what it looks like.

I had this problem on a Subaru. Chronic PO420 codes for years. It was the wiring connection for the U/S O2 sensor (even though my code was for the D/S sensor) Fixed that but cutting out the connector and hard-wiring everything with heat shrink connectors and the codes went away. The bad connector must have messed up the U/S sensor reading, tricking the ECU into thinking the D/S sensor reading was not right.

Definitely check your the wiring, for both the upstream and downstream O2 sensors. You can also get a more advanced OBD2 scanner (Wifi or Bluetooth) and an app like Torque Pro to read actual sensor values vs. time. That will help you compare the readings of the upstream and downstream O2 sensors (for both banks) and isolate the problem. You can get a Wifi code reader for $30 on Amazon and Torque Pro is $4.95.

 

[HomersCanyonero]

P0420 Catalyst System Efficiency Below Threshold

How to diagnose, repair, and info on symptoms and causes of a P0420 engine code which means the catalytic converter is no longer performing at a normal level.

www.obd-codes.com

OBD-II Trouble Code: P0430 Catalyst Efficiency Below Threshold (Bank 2)

Thanks for that link. it says:

Causes:
A code P0430 may mean that one or more of the following has happened:
(1) The catalytic converter is no longer functioning properly
(2) An oxygen sensor is not reading (functioning) properly
(3) There is an exhaust leak

And there’s a fourth cause which could be the writing harness.

I’ll keep diagnosing replacing the cheaper parts or repairing leaks/wire first until I get to the cats.

 

[HomersCanyonero]

The Car Scanner app seems pretty good for being free. I might buy their app for $7 to upgrade to all the other premium features.

the app is reporting good voltages on all O2 sensors.

 

[HomersCanyonero]

Problem is I don’t really know how to read the o2 sensor scanner readings.

 

[Rednexus]

You'll probably need to spend some time combing the internet to interpret the data. Here is a video on it:


It might also be better to export the data to a spreadsheet, then pull it into Excel and plot it that way. I spent a couple of hours yesterday doing that while trying to diagnose a MAF code (and ruled out a few things).

 

[HomersCanyonero]

Thanks fir that video. I’ve watched it several times and I was able to graph the rear 02 sensors as the video describes.

it looks like one cat is worse than the other but both cats don’t seem to hold the o2 voltage. They move up and down too fast.

So, I ordered two new oem integrated cats.

 

[HomersCanyonero]

And here are my last 4 wheel alignments with the Nitto ridge grappler tires. American Discount Tires keeps straightening my caster.

 

[HomersCanyonero]

Went to Berdoo Canyon dispersed camping. GX470 doing great with extended rear shocks and springs.

 

[HomersCanyonero]

Gx470 is at my Indy mechanic getting new oem upper left and right cats. Got them at McGregor Toyota at a good price and no upfront taxes.

Also, got OEM manifold gaskets just to be sure there no leaks.

Job complete...$200 labor to install. Now I wait to see if my P0420 and P0430 codes go away. Smog check due by early April.

 

[HomersCanyonero]

After 70 miles of driving, my emissions was ready and no more codes. I went to get smog check and everything passed California style.

So far, a hundred miles and no lights. It looks the cats were the root cause of my P0420 and P0430.

Total cost was $1200 including oem manifold gaskets, oem upper cats (left and right), and labor.

And I saved the old ones in case mine get stolen! Lots of thefts around my area.

 

[HomersCanyonero]

Found a little waterfall in a palm oasis at sheep canyon in Anza Borrego California. It got hot very quickly in the desert and I dehydrated despite finding shade and water.