Allright I got a 4.6..Service engine soon light came on. I read the code with my Superchip 1715..p0420 was the code Catalyst SYS Efficiency Threshold (bank1). I took it to a local shop and they said it could be the cat, or o2sensors..Its on my wifes 2000 expy.. Futher investigation would be needed to narrow it down!!

They also said they could replace all of it for 1000.00, and I thought I bet you could!!

They also told my wife that the expy has 8 02 sensors, I was thinking,,,did I hear that right?????

If it's bank 1 then shouldn't that one bank be where I should be looking??? the truck runs fine, it needs a mild tune up but that's it!!

Changing plugs and maybe some 02 sensors...

What do you guys think!!! any help brothers sure would be appreciated!!

 

That's a bad cat code. That's all the rear O2's do, monitor cat operation.

If the sensor harness is cut, well, I stand corrected.

Only FOUR (4) O2's on that Expy. Find another shop...you probably know to do that by now!

Without knowing vehicle mileage, the cat may be worn due to age, but other engine conditions can factor in as well. But, if this is the only code as of late, it's probably just age.

Bank 1 is passenger side.

 

Thanks Alfred. Its got over 140000 mi on her...I was thinking the cat myself but i haven't noticed any loss of power or smell or anything like that... What else would happen if you cat goes out??

 

If you are within 8 years of your in-service date (outside chance) and are less than 80K miles, the cat is still covered under warranty.

It ain't the downstream sensors.

A misfire or a bad upstream O2 sensor can cause the cat to get flooded leading to it's ruin. That just means it's no longer srcubbing the exhaust, otherwise, there is no change in vehicle performance unless the catalyst crumbles or melts.

A tech with a good scan tool can watch the upstream vs downstream switching ratios to see if the catalyst has failed.

FWIW, if you don't have emissions testing, it's not a big deal. Also, you can install either anti-foulers or MIL eliminators to fool the computer into thinking the cat is functioning so the MIL doesn't come on.

Steve

 

Thanks man..can you explain alittle about the anti-foulers and MIL eliminators?

Way back in the day I used to drive a old toyota forklift with anti foulers on the plugs just because it burned so much oil it would foul out the plugs..

I'm sure this isn't exactly in the same catagory as that,,right??

 

Actually, my Mom's Jeep kicked out that same code last summer. A friend of mine manages the local Cole Muffler and I took it to him to do a cat flow exhaust test and all was good. I replaced the upstream O2 Sensor for the bank it was on and reset the PCM.
The code has never come back.

PS: I did try to just reset the PCM 1st to see if it was a cowinkidink and it wasn't. The code came back within a week if I remember right.

 

Do you happen to know if its very hard to get to the upstream 02 on an expy?? I may just try that, reset my code and see if it returns!!

 

If it's a 4WD, it's a PITA to replace the O2S11. Go in through the wheel well.

Google MIL Eliminators and Anti-foulers for suppression of cat efficiency codes. It's well covered.

Steve

 

Bank 1 is passanger side. You will have to remove the passanger side tire for better access. My removal trick is. With Exhaust hot, spray PB-Blaster on threads where it threads into the exhaust pipe "bung". It will stink and burn off but no worries. Let the engine cool down and respray the threads and bung area again with the PB-Blaster. Let it sit over night if you can. The next morning, one more shot of the PB-Blaster and remove the O2. To date this proceedure has never allowed me to run into a problem. Believe it or not, I have gotten all O2's out with an open-end wrench. Still waiting for one that gives me a hard time, then I will have to buy the special O2 socket.

Good luck with the work,
TJKinCNY

 

Changing the plugs at a 100k is a real good idea if they have not been done.
I have 145k on my truck and I am considering replacing my front O2'S this spring. Running good but I think I am pushing the limits. I know by replacing them I should get better performance and MPG's. Along with that I will pulling my TB & IAC and thoroughly cleaning both. Now I'm think new injectors as well. I need Jbrew and some other members to point me in the right direction with the right injectors to buy.

 

https://www.f150online.com/forums/ar...r-install.html

http://mattstruck.com/sparkplugs/sparkplugs.html



Tjk - http://cgi.ebay.com/ebaymotors/_Car-...ht_3514wt_1491

https://www.f150online.com/forums/ar...ttle-body.html

 

Nice job, thanks Brew !

 

You can get them cheaper if you keep a look out. There's a few guys on eBay whom acquire Romeo crate motors and sell everything on top. I got the coils,injectors and complete wiring harness for $120 about 3 years ago.

They were new , but installed on the crate motor. They couldn't sell them as new. Mann - it's -1 degree's outside right now and I have NO fluids in my truck - Going to stick a heater under it.

 

Going to get much worse. They are forcasting from Michigan all the way to here in NY below 0 degree's. They are talking -14 here tomorrow.

 

Well I've got 3 layers on right now , two more layers and I'm heading out in the shop - I wonder if the computers still working out there, I left it on

Fortunately, I have 12 shop computers, all the same. I went thru one so far ..