Help with my catalytic converters
 

I have a 2005 G36 Sedan X model all wheel drive. I took the car to my local guy to read the codes and was told the top left and bottom right cats were bad, this car has four cats. I was also told since it was an X there were no aftermarket products and needed to order the parts from the dealer. The approx. cost in Toronto is $1,100 each time two plus a few minor clamps and gaskets plus labour for at total around $2,500. Is it true that there is nothing cheaper around for the X model?:confused2:

G35X Sedans only have 2 cats, and there are tons of aftermarket options.

You can go with Hi-Flow Cats (which cost 400-600 for a pair) or test pipes ($100-200 for a pair), if you wanna stay with having a catalytic converter, or you can look for a used OEM cat.

Install takes about an hour, so it should be at most $100 for labor.

It is my understanding that each side has two small cats referred to upper and lower for a total of 4. I will need to do some research to see if this is true. Thanks

i think you mean O2 sensors

There's only 2 catalytic converters and 4 O2 sensors (lower and upper).

If your code is P0420, it's more likely an O2 sensor. Same thing happened on my Subaru a year ago. P0420. Took it to the dealer, he said it was def a Cat and it would be $1100 to replace it. After getting access to AllData myself, I found out it was a $600 part and 45 minutes of work, so the dealer was adding a premium to the price. Either way, I didn't really believe it needed a cat. Replace the front O2 sensor and the code went away. Cost all of $50 for a universal sensor, just cut the wires off the old sensor and splice them in. Works great!

With some code reading devices, you can check your front and rear O2 sensor readouts. More than likely this is an O2 sensor issue. Go to Advance auto or somewhere and get your code read and tell us the number.

Thanks for all the help so far. I originally had a 138 and 158 code so I have already replaced the two down stream O2 sensors, cleared the codes and three codes came back, 138, 158, 420. I know the car has 2 upstream sensors and two down stream sensors but also the two cat pipes look to me like they have two small cats on each side. I will phone the dealer and confirm this as my mechanic pointed a heat sensor at them and determined the upper left (bank 1) and lower right (bank 2) were blocked.

They could be resonators as well. I'm fairly new to the g35x so I'm not sure.
Upstream O2 sensor is the one that died for me.

resonators only muffle the noise. They are after the cat and rear 02 so it does nothing in terms of CEL.


How sure are you they replaced the RIGHT sensors... the P0138 and P0158 should be gone when you replace those 2 almost on the spot.

I just did a rear 02 and a bank 1 sensor 1. Both codes went away right off the bat.

I swear by my Kinetix high flow cats.....they sound awesome noticed good gains fit well and still to this day are in good shape

I have a 07 g35x and mine has 4 cats in it. And they also need to be replaced.

Just wondering mileage you have for the o2 or CATS to go.

First you posted in the 03-06 Sedan forum.

Second your car has 2 catalytic converters not 4.

That is all. :thewave:

Test pipes/cat converter
 

Test pipes are the same length, same flange as the cats so they are compatible for when you install the rest of the exhaust in the further.