Codes P0420 & P0430

[h2100]

While they are in there, get them to also give you and document the cats inlet temps and outlet temps. Any good tech will have an infrared thermometer to easily do this with. It would add maybe 1-2 minutes of time to the diagnosis and that includes writing down/documenting the readings. Whatever they do you want all findings documented. Again, a good/honest tech will do that.

Cool. This is a real muffler shop so, I bet they will.

 

[OR VietVet]

Make sure when you do replace the sensors you use AC Delco or Delphi, IMO.

 

[swathdiver]

Hello All,

My 2010 Tahoe with 185,000 miles has posted these codes. Before I jump in and replace the rear, single, catalytic converter, does anyone have a different plan? I see they can be bought for $150-$250. Any brand preferences? MagnaFlow?

I wish to sell the car soon so I wish for a proper repair with no 'check engine' light.

I await your wisdom!

If you do not have any other codes, it's probably time to replace the cats. If you have one of those Bluetooth OBD II adapters with an app on your phone, you can often run a graph of the upstream and downstream sensors to test. The Upstream sensors should move rapidly once warmed up and the downstream sensors that measure the health of the cats move very slowly. If they move fast, the cat is not doing its job.

Your truck has three cats, one off each bank of cylinders and that third one under the passenger seat in front of the muffler. It's all one piece. I replaced mine a few years ago with the Magnaflow cats and y-pipe, 51578 is the part number for federal emissions. Got a great deal from @GotExhaust.com and if they've never been off before, pay an exhaust shop the $50-100 to replace them for you so they can deal with the broken exhaust bolts. Then sell your old cats (3) to the scrap man to offset the cost.

Cheap Chicom cats barely last a year.

 

[h2100]

If you do not have any other codes, it's probably time to replace the cats. If you have one of those Bluetooth OBD II adapters with an app on your phone, you can often run a graph of the upstream and downstream sensors to test. The Upstream sensors should move rapidly once warmed up and the downstream sensors that measure the health of the cats move very slowly. If they move fast, the cat is not doing its job.

Your truck has three cats, one off each bank of cylinders and that third one under the passenger seat in front of the muffler. It's all one piece. I replaced mine a few years ago with the Magnaflow cats and y-pipe, 51578 is the part number for federal emissions. Got a great deal from @GotExhaust.com and if they've never been off before, pay an exhaust shop the $50-100 to replace them for you so they can deal with the broken exhaust bolts. Then sell your old cats (3) to the scrap man to offset the cost.

Cheap Chicom cats barely last a year.

Good info!

 

[h2100]

A qualified shop can test the cat(s).

https://www.rockauto.com/en/moreinfo.php?pk=6776156&cc=2002727&jsn=2235

https://www.rockauto.com/en/moreinfo.php?pk=1323343&cc=2002727&jsn=2251

https://www.rockauto.com/en/moreinfo.php?pk=1323899&cc=2002727&jsn=2247

Rock auto has great prices. How many of each sensor do I need/which one is which?

 

[h2100]

A qualified shop can test the cat(s).

https://www.rockauto.com/en/moreinfo.php?pk=6776156&cc=2002727&jsn=2235

https://www.rockauto.com/en/moreinfo.php?pk=1323343&cc=2002727&jsn=2251

https://www.rockauto.com/en/moreinfo.php?pk=1323899&cc=2002727&jsn=2247

wait, nevermind. i'm guessing i need two of each. That's what you said, before and after...

 

[OR VietVet]

Plus the link will say upstream or downstream.

 

[h2100]

The repair shop says $2,200. They did not share data for the cats but they say they are bad but he said sensors are working. He insists to not use aftermarket stuff.

I understand for the sensors, to stick to Delphi, but I can get the Y with all three converters on it for under $400 from Rock Auto on web with a shop installing is for a few hundred. The brand is Walker as was recommended above.

Why would I not do this?

 

[OR VietVet]

If you have mechanical abilities and some tools and a place to do it, the job is not that bad. The best thing to do is crawl under there and spray a great penetrating fluid on the threads for any attaching bolts/nuts/screws at the front and rear of the Y pipe and at the sensors where they thread in the pipe if you decide to reuse them, I would not, IMO. If you replace them then just use the penetrant at the front and rear of Y pipe. Make sure the gaskets you need come with your parts, 2 in front and one in back or whatever attaches at the back.

 

[h2100]

If you have mechanical abilities and some tools and a place to do it, the job is not that bad. The best thing to do is crawl under there and spray a great penetrating fluid on the threads for any attaching bolts/nuts/screws at the front and rear of the Y pipe and at the sensors where they thread in the pipe if you decide to reuse them, I would not, IMO. If you replace them then just use the penetrant at the front and rear of Y pipe. Make sure the gaskets you need come with your parts, 2 in front and one in back or whatever attaches at the back.

Any issues with the Walker brand of stuff?