3.0 Duratec Catalytic Convertors trouble code

[coral191]

My 2005 Escape has around 133,000 miles on, is running great, but CEL is on and code reads catalytic convertors. I understand these are a common failure on this engine by this many miles.

The engine has 3 cats, 2 built into the exhaust headers with upstream & downstream O2 sensors and a tailpipe cat with no O2 sensor. I'm guessing it's mainly the front 2 in the headers.

Anyone dealt with this problem? Can you get to the exhaust header bolts on each bank without pulling the engine? Any other info appreciated

 

[adsm08]

First things first. Which cat code do you have? Is it a P0420 or a P0430?

Both manifold assemblies can be removed with the engine in place, but the rear one is a LOT easier if you can put it on a lift.

 

[coral191]

It's coding P0420. No lift, just floor jack & stands, but good to know it's possible.

 

[adsm08]

Ramps would also be nice. I have found that when a lift is not an option I really like putting the front wheels up on ramps and then jacking the rear up and putting stands under it so it sits level. You can actually get quite a bit of working space that way.

You need to replace the rear cat. Drop the Y-pipe, the one that runs under the engine, get it out of the way, and then you should be able to do the rest with a long extension, a swivel, and a 13mm socket. I generally use an extension that is about 2.5 feet long.

While it is not 100% necessary the job is made vastly easier by undoing to two roll restrictor bolts and the front of the rear driveshaft (if it has one). The roll restrictors are underneath, about even with the joint of the engine and trans, two round guys, one to the front, one to the rear. Taking those two bolts out will let you roll the engine forward and get you a lot more space to drop the cat out.

 

[coral191]

When you say "rear" cat needs replaced, do you mean the one on the rear exhaust header, or the very back one on down the tailpipe right before the muffler?

And if it is the exhaust header cat, should I also put in new 02 sensors on that one also?
NGK 02 sensors good for this vehicle?

 

[GentleRF]

I think he's talking about the one by the muffler.

 

[adsm08]

When I say the rear cat I mean the one bolted to the rearward head. You only have 2 cats. The unit in the tail pipe that you have interpreted as a third cat is just a resonator. It's more like a second muffler than anything else. Cats that far from the engine are ineffective because they don't get hot enough to work.

It probably wouldn't hurt to throw some new oxygen sensors in while you are there. They are generally speced for a 100K mile service life. I greatly prefer Bosch to NGK for pretty much any sensor. Bosch makes a lot of sensors for Ford, so they are almost identical to the OEM part but usually much cheaper.

Also, remember that the upstream and downstream units are not the same and you can get some really screwy running conditions during coast down if you mix them up. I have a handful of good cat monitor sensor in my tool box at work because some joker at one of the local independent shops put them in an upstream hole to fix a heater code or something and then the customer comes to me when their car runs like crap.

Also, you are likely to get some of the studs staying in the head and some coming out with the nuts. Either way is fine, and neither one means that you broke something. Even if you knew that already, I figure it's better to hear something you already knew than to have an "oh shit" moment while laying under your car.