(non-SHO) 2010, 238k miles, p0420 Code

[Joe_Cool]

This has been a great car, but I guess I'm getting to the point where it's going to start having a bunch of small things failing. So I have a few questions for people who know things, since I haven't gotten my hands on a haynes or chilton manual in all the time I've had it. Oops.



On a car this old, is it more likely that my problem is the sensor or the cat?

What troubleshooting steps can I take to determine which it is?

Where are the downstream sensors physically located? (I just replaced both upstream sensors, to clear p0135 and po155 codes)

Is replacing the sensor and/or the cat a job that a normal guy can get done in an afternoon, or something I'd rather take to a mechanic?


TIA for your advice

 

[FiveLeeter918]

just to confirm, when you say non-SHO, are you saying it's an SEL/Limited, or were you meaning something else?

The P0420 is typically a catalyst efficiency code, stating that the post cat sensor is seeing more airflow and fueling than it should if the cat were functioning properly. typically I've never seen this code up for a bad sensor, so I would venture that your catalyst has broken loose.

An easy backwoods method for test is to put the car on jackstands (while cool) and hit the cat with a deadblow a few times. if it rattles or sounds like rocks in a coffee can, you can bet the cat is bad.

You can also unbolt the mid pipe and shine a flashlight in there to see if you can see through it. There should be a porous honecomb material in there that encases the platinum, if all you see is a metal grating, it's gone.

IF this is an SEL/non-turbo model, I'm unsure of any aftermarket downpipes but you could have a shop weld in a new set of converters or buy a new mid pipe. I'm unsure if the cats on the SEL are modular or not.

 

[Joe_Cool]

Yeah it's a plain old SEL. I'll try the hammer test tonight.

 

[Joe_Cool]

So the cats are these vertical canisters right before the y-pipe, right?




They look like they bolt and unbolt, so maybe possible for a non mechanic. The sensors look relatively accessible too, so that's good.

Which is bank 1? In front of the engine or behind? No rocks in a coffee can sound from either of them, though. So I'm still at a loss as to whether the cat or the sensor is bad.

 

[luigisho]

If they come off that easily that is sweet. The old n/a SHO ones are usually integrated with a Y-pipe set up.

 

[Joe_Cool]

If they come off that easily that is sweet. The old n/a SHO ones are usually integrated with a Y-pipe set up.

yeah the bolts up top are kind of tough to reach, but they should be accessible with a socket extension once the y-pipe is off.

 

[Zpak]

So the cats are these vertical canisters right before the y-pipe, right?


View attachment 15213 View attachment 15214

They look like they bolt and unbolt, so maybe possible for a non mechanic. The sensors look relatively accessible too, so that's good.

Which is bank 1? In front of the engine or behind? No rocks in a coffee can sound from either of them, though. So I'm still at a loss as to whether the cat or the sensor is bad.

Bank 1 would be firewall side.

 

[Joe_Cool]

Obviously it's not a real fix, but I've been told I'm a retard for not using spark plug standoffs. Will that make it pass emissions? Do the 18mm ones match Taurus threads?

edit: Sorry, "non-foulers".

 

[luigisho]

Unless the cats are performing adequately I'm not sure if it will pass. De-foulers (anti-fouler, non-fouler) get it to run well-- sort of bypassing the actual ex gas readings. I'm not sure if they work if a sniffer is used at the exhaust pipe. Some places do an OBDII plug and check for emissions but others test actual gas output. Not sure if that will work or not.

 

[Joe_Cool]

Unless the cats are performing adequately I'm not sure if it will pass. De-foulers (anti-fouler, non-fouler) get it to run well-- sort of bypassing the actual ex gas readings. I'm not sure if they work if a sniffer is used at the exhaust pipe. Some places do an OBDII plug and check for emissions but others test actual gas output. Not sure if that will work or not.

They still use the tailpipe sniffers? I haven't had that since the 90s lol

Here all they did was plug into the OBD port.

 

[luigisho]

Some places do. Most have probably moved on to the OBD method. I haven't had to pass emissions testing since I moved here a long time ago. Lots of ocean wind blows that stuff away.

 

[ticoscen]

2010 SHO PP with no CEL but has a tune on it and needs the emissions test. Maryland has the self serve kiosks now. In Maryland, I suspect the scanner is a shallow scan only looking for CEL or emissions errors, right? So, no need to down grade the car to stock before running the simple scan. Anyone try this in MD yet?

 

[Zpak]

2010 SHO PP with no CEL but has a tune on it and needs the emissions test. Maryland has the self serve kiosks now. In Maryland, I suspect the scanner is a shallow scan only looking for CEL or emissions errors, right? So, no need to down grade the car to stock before running the simple scan. Anyone try this in MD yet?

I passed in Indiana tuned. As long as you have no CEL’s and all emission monitors are set to complete you’ll be fine. If you’re catless you can’t have the downstream O2’s tuned out.

 

[ticoscen]

I passed in Indiana tuned. As long as you have no CEL’s and all emission monitors are set to complete you’ll be fine. If you’re catless you can’t have the downstream O2’s tuned out.

Cool. I should be OK then. Livernois keeps saying I have to go back to the original MAP and stock tune before going in. I don't think that is necessary. I have all the cats and two four legged cats in the house. I'll go to the kiosk. They just do ODB at the main and remote test stations. If you go in to an inspection station, they do use mirrors under the car etc. looking for cats and mufflers.