Hi guys. '12 g37xs, 92,000 mi, i'm not a car guy / can do oil changes / brakes.

-6 months ago i got a P0420 code, immediatley after filling up 2 gallons of premium gas at a generic station. (only had enough $ for 2 gallons) The check engine light went away after 1 day, attributed it to bad gas, didn't think anything of it.

-2.5 months ago I had a $2,200 repair for a bad vvel valve causing car to be in limp mode, dealer ran all sorts of test, never mentioned anything about a p0420 code or catalytic converter.

-2 days ago, check engine light came on again, immediately after putting only 2 gallons of premium gas into my car. It was a P0420 code, and the local parts store cleared it. This time however, afterwards when i try to accelerate between 0-30mph it takes a heavy foot on the pedal and 2.5k-3k rpm's. No noises or vibrating.

Afer I get past 30mph the rpm's settle and it's more of a normal acceleration. This accleration type issue has happened before since my original code in febuary, but only on isolated instances, maybe 5 times total.

As it stands right now the issue happens every time. Dropped it off at firestone, called back 8 hours later they said couldn't find any issues, so I explained to the new associate the problem including the code (even though it's cleared now)

They called me back 45 mins later and said magically they can duplicate my acceleration issue now, and I have a clogged cat converter, and need a new 1, and possibly 2. They also said after they replace them, they have to figure out why it went bad, because it shoudn't have with my cars mileage. They also said they won't install generic brand Catalytic converters. To be frank I don't have the money for a big repair, and will have to ask family for help. I'm not sure if they're trying to scam me and I should take the car to a muffler shop / dealer?

What do you guys reccomend I should do? Here is a listing of the p0420 codes, and thanks for your help guysP0420 Symptoms

• Check Engine Light is on
• Lack of power from the engine
• Decreased fuel economy
• Rotten egg or sulfur smell

P0420 Causes

• Faulty oxygen sensor
• Worn and internally failing catalytic converter
• Leak in exhaust system
• Leaded fuel was used where unleaded was called for (unlikely)
• A damaged or failed oxygen / O2 sensor
• Downstream oxygen sensor (HO2S) wiring damaged or connected improperly
• The engine coolant temperature sensor is not working properly
• Damaged or leaking exhaust manifold / catalytic converter / muffler / exhaust pipe
• Failed or underperforming catalytic converter (likely)
• Retarded spark timing
• The oxygen sensors in front and behind the converter are reporting too similar of readings
• Leaking fuel injector or high fuel pressure
• Cylinder misfire
• Oil contamination

 

Replace the cats. Go with aftermarket high flow cats. They can be had for $500-600 a pair.

you'll gain power and get rid of the check engine light with a brand like fast-intentions.

Or you can find a used oem catalytic converter here on the classified for sale section for $100-$300

 

Did they at least refer to page EC-329 of the FSM?

https://www.nicoclub.com/FSM/G37/Sedan/2012/EC.pdf

Perhaps you should read it!
Going to Firestone is like going to Jiffy Lube?
Poorly trained, poorly paid but they are cheaper than the dealer.

Why didn't you at least go back and get an estimate of the problem from the same dealer?

Telcoman

 

Dealer is about 30 mins from my house, firestone is walking distance. I was able get the car in same day at firestone. Also the cost of the dealer. I'm going to call some more places for quotes tomorrow.

 

Firestone called me and said both my converters are bad. They said they used some thermal gun to check, they didn't take them off. They want $2,100. They said something must have caused them to go bad. **** my life. Going to make an appointment at the dealer.

 

Can anyone link me a website to buy a pair for the left and right side? Nothing fancy, I'm not a car enthusiast, cheaper the better. 2012 g37xs sedan

 

https://www.ebay.com/itm/263803447023 $260 for a new pair on ebay?

 

As mentioend by Qman above, Your best bet is to keep an eye on the classified here, they come up very often and sell quickly and a pair is usually just a couple hundred dollars on average. Maybe post a WTB as well as a bunch of people on here probably have them sitting in the garage and just haven't bothered putting up an add.

 

Need to get this fixed this week. I don't trust buying used auto parts. Can you recommend a website?

 

I just bought a set here for $160. I would get set from the classifieds

 

Absolutely nothing wrong with buying used catalytic converters here on the classified. Most of the guys that post it up for sale have upgraded to test pipes or high flow cats and generally their factory catalytic converters usually have really low mileage (under 70k miles). I actually still have my factory cats but I plan on saving them for when I decide to return the car back to stock to sell it.

Check these out.

https://conceptzperformance.com/items.php?c=5&p=326&page=1

https://www.z1motorsports.com/exhaus...rs-p-5405.html

https://www.z1motorsports.com/exhaus...ts-p-4204.html

https://www.z1motorsports.com/exhaus...7-p-10141.html

You'll want to look for HIGH-Flow cats. They can be had anywhere from $300-$600 depending on brand. I have Fast-Intentions. Good quality brand. They are on the higher end of the price range. They are built to order meaning you may have to wait 8-12 weeks after placing a order before they get delivered to you. If you do not want to wait that long than there are multiple of other brands.

I have been running Fast-Intentions high-flow cats for 3 years now and the only time I had a check engine light was due to a exhaust leak. I bought my FI High-Flow cats used from another member and they were developing a hairline crack over time. I got it removed and sealed the crack by paying a shop to weld over it and everything is good.

My car is a 2011 G37S RWD with 90k miles. I've had the FI HFC installed since ~35k miles.

 

Anyone have any experience with this one? $298 for the pair and free shipping.

https://conceptzperformance.com/top-...at_p_38033.php

 

This thread has turned into this thread right here: https://www.myg37.com/forums/g37-sed...converter.html

No need for both, OP. I'm closing this one.