Mr.Jones

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