I got a service engine soon light the other day, so I checked it with my Diablosport tuner. I was only getting the P0430 code, so I pulled both driver side o2 sensors and cleaned them. I cleared the codes and it was good for a couple of days. Now today I am getting both a P0430 and a P0420 code.

A little background on my truck - it has 192000 Km on it and I replaced the 4 cats with 2 Magnaflow ones last year as my cats were pretty much melted and broken apart (had a misfiring issue that was taken care of after some time - new plugs, COPs, boots, injector cleaning/leak test, motor vac). The truck runs fine now, sounds fine, fuel economy is normal, idles smooth. But I have these 2 codes... Should I just replace the downstream sensors? I am pretty sure that all the o2 sensors are original. My tuner is not currently installed so I am running a factory tune.

When I pulled the driver side sensors the upstream one was blackened up some, and the downstream one was pretty white. I am not sure if this is normal.

Thanks in advance.

 

Your story is common among people who have used Magnaflow cats. We sold a lot of units over the last couple years that contain Magnaflow cats and we have had to warranty out most of them. Magnaflow is one of the aftermarket companies that coats their own catalysts. When they do this they are motivated by keeping their costs down and the profits up. Their catalysts are loaded with cheaper metals like palladium, enriched with cerium and zirconia to keep the CEL off for a while, and are just all around cheap, but with a quality appearance. I would equate them to a Hyundai car. Thy make a nice looking product that has the appearance of quality (nice box, clean appearance, professional look), but when it comes to quality and durability further down the road, they start to show their true colors.

O2 sensors should be replaced every 80,000 miles, which means yours should have been replaced twice. When things like misfires occur, carbon deposits can form on the sensor element, having a negative effect on the accuracy and responsiveness of the sensor.

My advice is to replace both upstream sensors, since they are the ones that are obviously fouled, and they are the ones that control the fuel to air ratio final adjustment. Even a discrepancy of as little as 5% can damage the converters by causing deposits to form on the catalyst surface. These deposits cannot be removed by any normal means.

Once that is complete, we have some cats that will actually last. Most cats have a 2 year warranty assuming your vehicle is kept properly tuned. Ours (all of ours) have 5 year warranties with the exception of products that contain Magnaflow or Catco units. Ours are designed to last longer and work better, and not to quit working a year or two down the road.

Your story is very common.

 

Make sure your engine doesn't have any vacume leaks-thats one cause of the codes. If you are convinced your engine is running correctly, the problem is your cats. I had the same codes on a Ford Cougar. The engine ran great--it was just that the cats are less effective after 100K miles. Unless you are one of thoses tree hugging green guys, I would suggest getting MIL eliminators.
Chris
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I Would like to keep the cats for sound purposes, but price may be an issue for me. I'll replace all 4 o2's as they are all way overdue. If the problem persists I may have to just remove the cats for now until I can afford to have some good ones put back in. I don't need the MIL's as I can turn off the rear o2's with my tuner.

 

Besides which Mil Eliminators are illegal. And what does having cats have to do with saving the environment or saving trees. We have converters so that we (human beings) can breath without dying on carbon monoxide poisoning. The environment could care less.

 

Update:

Today I ran a can of Seafoam through the PCV during lunch. Then when I got home I installed 4 new Bosch O2 sensors. Cleared the codes, reset the computer, and took it for a drive. So far so good. But before it took a couple of days to come back on. Tomorrow I will put on a good 60 km or so. Hopefully this works.

Thanks for the hope so far

 

Good luck to you, hopefully that takes care of it. Using the Seafoam was a great idea too, that might help the cats work better. It will take at least two drive cycles to know it it work, with a drive cycle starting from a cold start and getting to full temperature. To and from work should be enough depending on how far you have to drive.

 

The weird thing is when I went to clear the codes using my tuner it said that there were no codes.... So I wonder if the Seafoam cleaned up what may have been "stuck" in the cats and resolved the issue....

Oh well I needed the o2's anyways. Fingers crossed that I am back on track.

 

CEL came back on last night...

I loaded my tune back on just to see if maybe something was not right when I returned the truck to stock using my Diablosport.

How long can I go with it like this? Will it hurt anything? I would like to get new good cats, but may not have the money required for a month or so.

 

So long as you are sure the truck is running fine now and your Long Term Fuel Trim is currently within 5%, you can drive it around with that light on without hurting anything.

 

Basically: I got code; ignored it for months; replaced rear o2 senors, did nothing; cleaned front o2 sensors did nothing; finally quite being lazy, studied and read obd codes on post cat o2 sensors; bank 2 (driver) was clogged; once removed, I verified, as material was falling out, bought ford OEM cat, $936; all fixed! Truck runs with power, 139k, .2014 5.4L 3v, 2wd,

Top one passenger O2, good; bank 2 below, clogged;

Normal rear o2 sensors in my wives car

Cat material pouring out;