P0420

[Archaic2021]

Got the dreaded P0420 code on my 97 5.0 c1500.

The truck had a miss for awhile on cyl 2 and that's all fixed. Stock exhaust.

What would be the signs of a clogged converter...a bad sensor.

Truck seems to run fine just hate the light.

What benefits are there to removing the cat all together?

 

[RichLo]

What was the miss problem? Ignition? If you were sending raw fuel into the exhaust you could have burned out that cat.

Can you data-log both the downstream o2 sensor and the upstream o2? The upstream should be bouncing around between .1 and .9 volts regularly and rhythmically and the downstream should be hovering at .1 with some bumps up to around .5 once in a while. If the downstream moves around and follows the upstream then your cat is burned out. If the downstream just reads a flat 0 then that o2 sensor is bad.

 

[Archaic2021]

What was the miss problem? Ignition? If you were sending raw fuel into the exhaust you could have burned out that cat.

Can you data-log both the downstream o2 sensor and the upstream o2? The upstream should be bouncing around between .1 and .9 volts regularly and rhythmically and the downstream should be hovering at .1 with some bumps up to around .5 once in a while. If the downstream moves around and follows the upstream then your cat is burned out. If the downstream just reads a flat 0 then that o2 sensor is bad.

It was a bad poppet style injector. The miss would clear up at higher rpms. I added new style injectors.

I have a very very simple scanner I'll have to see what it can read.

 

[any4xx]

Just FYI I bought an exhaust back pressure gauge off of the jungle site for under $20.00. Since my truck had sat for 12 years because of a poor-running condition I felt it was worthwhile to check EVERYTHING. Might be money well spent in this case?

 

[RichLo]

If your cheap handheld scanner cant take the right readings, I highly recommend this product, OBD Link MX+...

OBDLink® MX+ - Outstanding Bluetooth-Compatible OBD II Scan Tool

The OBDLink® MX+ is the top-of-the-line OBD II scan tool to use with forscan and comes with bluetooth. Get one here today and gain access to your vehicle!

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You can download free programs onto your phone, tablet or laptop and connect via bluetooth. That scanner is also very fast which helps a ton when data-logging and using the gauging features.

 

[Archaic2021]

So my little auto link had the following

02s11 (v)
02s12 (v)

02s13 (v)
02s21 (v)

All were bouncing between .1 and .9 So cat is prolly burn out and gone.

Could I run a sprak plug spacer on it to try and trick the rear 02?

 

[Archaic2021]

I've seen people run the spark plug non fouler on deleted cats might as well try it on mine since the cat is bad...from the way it sounds it maybe mostly gutted anyways lol

 

[RichLo]

What do you mean running a spark plug? like a spark plug in the exhaust?

And a spacer MAY help that sensor catch a little less but it will still be a constant battle with the CEL, at best you would just be resetting it less frequently.

Then there is always that tab of black tap over the light to make you feel better, lol.

 

[Archaic2021]

What do you mean running a spark plug? like a spark plug in the exhaust?

And a spacer MAY help that sensor catch a little less but it will still be a constant battle with the CEL, at best you would just be resetting it less frequently.

Then there is always that tab of black tap over the light to make you feel better, lol.

No its a spark fouler? it's more of a less a spacer that moves the sensor away from the exhaust so it doesn't detect as much air flow?

I drive the truck 90 miles a day I need the CEL lol

 

[RichLo]

You have some options (in order of correctness)

1: Fix it correctly
2: Tune the computer to delete info from the downstream o2 (you can do some other things while the tuner is in there)
3: Run with the spacer thing and probably have similar results as without. And just leave your scanner permanently plugged in so you can delete the code as soon as it pops up every time.
4: Tape over the CEL and turn up the radio when the truck makes a bad noise