P0420 wont leave me alone.. (9 Viewers)

[alia176]

I'd simply swap the post cat O2 sensor from left to right and see if the code changes sides. If not, then your cats are clogging up, which is normal for high mileage rigs. If it wasn't such a PITA to remove the exhaust manifold+cats, one could wash the cats in a proper washing solution (lots of info on the net).

From what I learned, cat converters just doesn't go bad, they get coated with grime and lose their efficiency over time and the O2 sensors are simply the bearers of bad news. The materials inside the cats are precious metals and they don't vanish over time or get wasted. I'm having the same codes for both banks on my GF's ride with 100k miles and I KNOW we caused the cats to get clogged up by chasing what turned out to be a bad fuel pump over few months. She ran lean for a while so we coated up the cats pretty nicely with gunk.

 

[taco47001]

I've been following this thread and a few others on here related to p0430 and p0420. A few months ago we drove ours to Florida for vaca. Total miles round trip approx. 1,700. While down in Florida, it threw a check engine light which I had read at auto zone and was a p0420. While driving home, the light went off and stayed off. After returning home it would come back on intermittently but was now showing as a p0430....so the bad cat has mysteriously moved itself to the other side of the truck????? I say nay. It has to be a sensor at this point. I had previously replaced the O2 sensors, cleaned the MAF, and verified it was reaching proper operating temps via tech stream. My next step was going to be spark plugs. Instead I decided to try the gas cap next as this was much easier than replacing the plugs. We'll, to my shock and awe...three days now and what would have normally caused the light to come on in recent weeks....has now become a much more enjoyable drive without the Yellow fail lights (check engine etc) mocking me. I will verify this fix through TechStream next week but so far, so good. My point....... try replacing your gas cap.

 

[kbahus]

I would give it more time before concluding the gas cap fixed your codes, let us know how it turns out. Was your sealing gasket visibly cracked?

For the post above cats do go bad, I have seen plenty that have literally come apart and cracked into pieces. Sometimes it causes a rattle, sometimes it results in the vehicle barely running. It happens. I wouldn't waste my time trying to clean cats, but that is me.

Anyone else install the spacers yet? Reports?

 

[tacoduck]

I would give it more time before concluding the gas cap fixed your codes, let us know how it turns out. Was your sealing gasket visibly cracked?

For the post above cats do go bad, I have seen plenty that have literally come apart and cracked into pieces. Sometimes it causes a rattle, sometimes it results in the vehicle barely running. It happens. I wouldn't waste my time trying to clean cats, but that is me.

Anyone else install the spacers yet? Reports?

I spent some time with a mechanic that has a really nice OBD reader. We looked hard at the right rear o2 sensor. its working fine, its just reading high. I thought about replacing the upstream o2 sensor, but he said it's doing exactly what its supposed to be doing. Again, I have a code for p0158 which is right rear o2.
He thinks that the cat isn't doing its job, and prob needs to be replaced. Im tired of throwing money and guessing at the problem for a stupid emission reader.

I just put a spacer in my right rear 02 sensor. disconnected the battery for 10 minutes. Ill report back with results.

 

[taco47001]

I would give it more time before concluding the gas cap fixed your codes, let us know how it turns out. Was your sealing gasket visibly cracked?

While I deff agree there needs to be a bit more time but as I said, I will verify on Monday via TechStream. For the past few weeks the light became very predicatable for coming on during certain trips we take quite frequently...i.e. Taking our kids to school. Trips like this were total drive time was 10-15 miles or less would consistently trigger the light. When my wife would drive to work, a 39 mile one way trip, the light would always turn off. Via TechStream I could see the current status of the code as "history" but not "current" when the light was off. When I would take the short trip with TechStream running it would show "pending" and ultimately "current". Within the current and cumulative status screens the cat status would either have a thumbs up or down depending on which drive cycle I was checking. While I know it's not "fixed" until confirmed via TechStream and ultimately when the light no longer comes on to mock me, I was simply echoing what others on this thread and others have said. Keep it simple first. The dealers going to tell you "Cats bad, $2500, sorry", when it's not.

And yes, after close inspection of the cap the rubber seal was dry rotted and cracked in places. This was why I chose that route first instead of pulling/ checking/ replacing the spark plugs. The cap was $23.


This person had a similar code (p0158)

CEL Light (saga) and Codes - P0158, P0606 - Club Lexus Forums

 

[kbahus]

Please keep us posted!

 

[alia176]

I would give it more time before concluding the gas cap fixed your codes, let us know how it turns out. Was your sealing gasket visibly cracked?

For the post above cats do go bad, I have seen plenty that have literally come apart and cracked into pieces. Sometimes it causes a rattle, sometimes it results in the vehicle barely running. It happens. I wouldn't waste my time trying to clean cats, but that is me.

Anyone else install the spacers yet? Reports?

We are using O2 spacers in the GF's rig to no avail.

 

[kbahus]

For P0420/P0430 codes? Any other codes stored?

 

[landarcht]

I know this is a very old post, does anyone know what type of spacer or order for 2005 100 series? I think mine has flange and threaded? I used to have P0430 code for over a year, since replacing the O2 sensor on Bank 2, it is throwing P0156 (O2 sensor) code now. I drive it daily, no issues.

 

[WaterGeo]

I know this is a very old post, does anyone know what type of spacer or order for 2005 100 series? I think mine has flange and threaded? I used to have P0430 code for over a year, since replacing the O2 sensor on Bank 2, it is throwing P0156 (O2 sensor) code now. I drive it daily, no issues.

I am having a consistent P0420 issue after replacing all the O2 sensors. I’m thinking about replacing the gas cap and adding a spacer to both of the rear sensors. So I second @landarcht’s request for the spacer specs that everyone is referring to.

 

[GXO]

I like the 90 degree spacers so the O2 sensors don't hit heat shields and stuff. You only need to space the downstream O2s.

 

[landarcht]

Here are some photos, of mine. I was told by my mechanic that the existing flange plate seems rusted and he was afraid of breaking it if removed by force. Not sure if I need to replace a section of this pipe as I'm trying to avoid having to replace the entire run including the

cat.

 

[WaterGeo]

I like the 90 degree spacers so the O2 sensors don't hit heat shields and stuff. You only need to space the downstream O2s.

Something like this @GXO ?
It doesn’t seem like the best website to source from but this is the best example I have found for what I think you are talking about.

Thanks for the help!

O2 Oxygen Spacer Sensor Extension Multi fit 90 Degrees 02 Fits Toyota Tacoma Etc Generic

Feature:Check engine light to fix M18 x 1.5 sensor vulnerabilityThe multi-part O2 sensor gasket for Toyota Tacoma tacoma and other models uses this flange form. This kit can be used in few different ways as shown in the picture above.With dedicated tools, perfect precision and repeatable...

jcarpart.com

 

[GXO]

yep!

 

[Rednexus]

You might have a problem in the wiring harness for the O2 sensor, if it is throwing the P0156. It could be corrosion in the connector or something else with the sensor that is not right.

However I do have the 90-degree O2 spacers in my GX with the front two cats totally removed (due to headers), and I get no CEL's! But, if you are getting the P0156, it might not go away even with the spacer if there is some other sensor/wiring problem. The spacer just tricks an otherwise properly-functioning sensor into thinking there is less unburnt fuel in the exhaust.

 

[landarcht]

So are you suggesting the wiring harness be replaced? Is there anyway to remove the corrosion in the connectors?

 

[Rednexus]

So are you suggesting the wiring harness be replaced? Is there anyway to remove the corrosion in the connectors?

You should inspect the wiring harness and connector for signs of damage or corrosion. If the connector is corroded you should be able to either just bypass it with some heat shrink connectors or buy a replacement connector online and splice it in.

 

[estoddart]

You might have a problem in the wiring harness for the O2 sensor, if it is throwing the P0156. It could be corrosion in the connector or something else with the sensor that is not right.

However I do have the 90-degree O2 spacers in my GX with the front two cats totally removed (due to headers), and I get no CEL's! But, if you are getting the P0156, it might not go away even with the spacer if there is some other sensor/wiring problem. The spacer just tricks an otherwise properly-functioning sensor into thinking there is less unburnt fuel in the exhaust.

What 90deg spacers did you go with? I'm about to install DT headers. Thanks!

 

[Rednexus]

What 90deg spacers did you go with? I'm about to install DT headers. Thanks!

I bought some off of Amazon. I looked a few months ago and they are are no longer sold there (probably to only being legal for off-road vehicles....). It also appears like there aren't any on eBay right now. Mine are still working great a year and a half later.

A quick Google search found the same type of extender I used: Garlaven 90°O2 Oxygen Sensor Spacer Engine Light CEL Check Bung Mini Catalytic Converter Generic - https://www.garlaven.com/products/90-o2-oxygen-sensor-spacer-engine-light-cel-check-bung-mini-catalytic-converter-generic-virm?variant=03190908-9fa9-46b3-957f-78a301b35180&gclid=Cj0KCQjwyOuYBhCGARIsAIdGQROYdJ9VXSZ-ueg1YZWu-97NOJysSH0WoK_BoWT2DsgaI41Zyktlv7caAtvvEALw_wcB

I have not used this website so buyer beware - but it's the same style of extender I have. Probably comes via China Post.

 

[Sixto Lezcano]

I used straight version, but this company has both shapes and I haven’t gotten any errors since installing. OEM headers, not DT, but they did work.

O2 Simulator Mini Cat Cel Fix stainless steel Rear O2 sensor simulator.

O2 Simulator Mini Cat Cel Fix, Big Daddies Garage Mini Catalytic Convertor Rear Oxygen Sensor Simulator is the best and easiestway to clear p0420 / p0430 codes for bad or missing catalytic converters. Just screw it the o2 simulator mini cat into the existing exhaust then srew in the oxygen...

www.bigdaddiesgarage.com