Code P0420- Did the dealer kill my cat?

[Tomkat1127]

Before I have someone attack me for animal cruelty, no the dealer didn't kill my feline pet. I am talking about my catalytic converter.

I install a Stroumung CBE with CNT catted DP (for 5 EAT), Innovate LM-1 and G3 AFR guage and had it pro tuned on 9-26-11. No issues until around Thanksgiving when the dealer did my 30K service which included a injector and top end cleaning (per the advice). About 350 mile later I get code P0420 (Cat. efficiency below threshold). Since it was aftermarket exhaust they would not/could not touch. I understand this, but I did make the statement that all was fine until their service and perhaps their harsh cleaning chemicals destroyed my rear O2 or worse the cat. I know they are "supposed" to be converter safe, but the service manager did agree it could have killed my O2. They did clear the code and told me to drive it and see if it came back. I set one of my trip meters at that point. It never came back until last week, when we had a little snow/ice and I had to idle and do a lot of stop and go driving. On down the road a few miles and a 50-65mph the light comes on, cruise flashes, and there goes the traction control (why and the hell a CEL turns off traction control is beyond me, stupid IMO). Pull off to Advance at 1890 mile since the last time with another code 420 (at this point I am calling my car a stoner). Today 665 mile later (yeah I drive a lot) it pops back on, I have my old Actron with me, so I pull off at a gas station only to figure out my scan tool is not Can BUS compatible. Back to Advance, grab theirs and turn it off. It is now a nuisance and most be stopped.

 

So what do you think my chances are that the converter is gone or just a rear O2?

Any harm in turning that DTC off in RR and flash ECU? I have already done this tonight but not drove it and have my tuner's map saved. Can't see why not, many have catless systems which put it way below efficient! LOL. It worked fine once, I would rather not turn codes off.

 

This part is bit more suited for the tuning section (mods move my post if you wish). Now I may be imaging things but since the cooler weather and winter blends of gas, my mileage has dropped about 2 mpg (not untypical). Could I be dumping too much fuel in? AFR via LM-1 is 12:1 under mid-heavy accel, 14-15:1 under cruise on flat. Tuner did mention to me that he always removes all CL to OL delay. I can watch it on the highway, I can be at about 14.7 and watch it drop to 13 the second throttle is increased for a hill. Should some be added back in?

 

Any comment is appreciated. My search of the board, didn't reveal much insight on this topic.Thanks.

[fahr_side]

I think if your dealer's chemicals had poisoned the O2 sensor, the front one would have died first since it's in front of the cat. Not all metal substrate cats are created equal and not all O2 sensors are equally sensitive. IIWY I'd just disable the code in RR and be done with it. My car ran without a code despite the Invidia catted DP I use. I still have the code disabled because I'm aware that it could just come up one day and I'd rather not have the hassle when out on a trip somewhere. Sod's Law says that I won't have my laptop with me the day it happens!

[Tomkat1127]

Thanks fahr_side.

 

I didn't think about that perspective. It should have killed my wideband O2 first. However, as you kind of said, not all O2's are built the same or have the same life.

I was worried that the aftermarket cat in the DP, which is not as large as stock and probably not of the same quality was/is gone. If that is the case then, it would be gutted.

By the time I posted last night, I had already flashed the ECU with DTC P0420 disabled. However, if I am still dumping in to much fuel due to colder denser air, I will want to fix that and maybe add some CL to OL delay back in. In hopes of getting a little mileage back.

My tuner was conservative and probably added lots of fuel to keep me from ever getting any knock.

 

You are always right on the fact that it will pop on at the worst time. I don't carry my tuning laptop with me at all times, but did have my scan tool. Which I figure out at the last moment is not CAN BUS compatible. Now I got to trade up or sale and buy new. Can't live without checking my own codes when I need to.