Hey guys my car has recently been throwing the P0420 code quite often, maybe once every week or two? The only mod to my car is the exhaust, I have a u-bend delete, a resonator delete, and a flowmaster 40 delta flow muffler. I had a couple questions about the code and the cat. What does that code mean, my cat is bad? plugged? I am ordering a ZZP PCM and Wizaired Intake right away so that code will be no more after the PCM, but I am wondering if I should be putting in a high flow cat? or possibly removing the cat and be done with it? what effects on performance and/or gas mileage will the high flow cat or no cat have? And lastly, will I see a decrease in performance or gas mileage when the code is being thrown currently?
THanks so much and looking forward to your replies
-Devin

 

Hello, how many miles on the CAT?? Many things can cause a CAT to foul and plug the screens. Sounds like all you need to do is do a pressure test and determine if the CAT is plugged. If so it's a relatively inexpensive issue to replace with a new one. I always use a High flow with Metallic coatings as they are able to resist higher exhaust temps and absorb road vibrations, the factory ceramic composite are more fragile and damage more easily.. Actually melted my ceramic coated screens together from high exhaust temps and the CAT only had perhaps 1000 miles on it.

Keep a CAT on the CAR... save the planet one car at a time

 

The P0420 code is telling you that the cat isn't as efficient as it should be, but it may be that the U-bend delete is flowing higher, and that the car isn't used to this. Try leaving the battery disconnected for 30 minutes, and then reconnect and start it up. It may run rough, but should even out, as it learns the new exhaust system, also do this when you get that new CAI.

I'm running no cat, and wish I hadn't removed it.

Without the cat, and the normal ZZP tune, I now throw a code that the rear O2 sensor is missing. An emulator would solve this, but only on certain models years, and I don't want to send the pcm back in just to remove one code. There is also an odor issue without the cat, prepare to have your exhaust smell like a lawn mower.

Performance wise, there seems to be a bit more grunt, and the exhaust sounds better. I haven't noticed much of a shift in fuel economy, but my car has never been that efficient anyway.

 

Aren't there very strict emission laws in Canada?

 

Oh yeah it's strict... I would not remove the cat, unless you're willing to have it put back on every 2 years for inspection... Also, if you get pulled over by MOT for an inspection it's an automatic $400.00 fine for tampering with an emissions system... Just get a hi-flow cat, I've got one (Magnaflow) and love it...

 

My guess is a failing stock cat. If you have to replace the CAT, I would recommend you buy a ZZP downpipe with high flow cat and it bolts right up. The downpipe has a bigger inside diameter then the stock one. More flow! Down side is, high potential exists to throw that same code, but there are a couple of fixes (easiest fix is to have the PCM re-tuned to ommit that code, the other I've seen is to space the O2 sensor out of the exhaust stream).

 

Being that you live in Canada if you got a high-flow cat and downpipe from ZZP I would check out Will at Overkill to see about tuning your car

getoverkilled.ca

 

Highly recommended... I got my tune from Will and it is fantastic... He tuned it in the car and the whole process took about an hour... And the support he offers is excellent...... Far superior to my last Intense canned tune...

 

Well Canada Isnt as STRICT as you all Think. Its all On the province you live in / city. Here in Manitoba/ Winnipeg Ive had No cat/Res for almost 2 years. never been hurrassed, Drive buy cops all the time they just rather look at the Monte... In manitoba Thiers No inseptions evry 2 years? I think thats Only In Ontario. ontatio Is More Strict then anywere in the STATS lol. Even On Semi's You should hear all the story's i hear from truck drivers,

Your Mostlikly Will be Pulled over For Being Stupied. Reving High/racing/driving stupied. then they lay you as many tickets as they can.

I agree not having a cat isnt the greatest Idea for our Planet. But I dont wanna replace a Cat again. soo I Bought 2.5" Stainless Offroad Never have to worrie about it.

 

If you don't need the Cat then I wouldn't use it either.