Update:
Okay, got an update. It's the Cat Converter. They're replacing it but it will take a day or two to get the part in.

Why would a cat fail at just 14k? Any ideas? Could the previous owner have done something really bad that could trigger it?

Also, would a new cat help with the fuel economy? I just noticed that the loaner i have is doing significantly better on my daily trips than my own car. (At the rate of 3-4mpg better)

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Howdy!

I just bought a new (used) G with 14k miles on it from Carmax. (Carfax/Autocheck and Infiniti records all came out clean). They filled it up with regular against my request so i'm currently stuck with it, driving cautiously, until the tank runs dry.

2 days after i brought the car home, i was driving around and had to get on the pedal to avoid getting rear ended. Shortly thereafter the SES light came on, it's showing a P0420 code (Cats).

At 14k, could this really be the cats? I'm thinking it's possibly just from the bad gas. I'm thinking of just resetting it after i put on the premium stuff. Is that a good idea, or should i just take it in for servicing anyway? (and pay Infiniti for the diagnostics)

Thanks!
- Mike

 

I doubt it is the gas. The car is designed to run "optimally" on premium, so there should only be degradation in performance if a lower grade fuel is used. Isn't the car still under some sort of warranty? I'm not sure of the error code, but it could also mean a bad sensor.

 

^^+1 I agree with Terry.

Also congrats on your new to you G

 

420 means that there is not a sufficient reading on the rear O2 sensor. Its often a code that may pop up when HFC's are installed and the rear O2 sensor thinks the cat isnt working due to the much higher flow. You may have a bad cat or bad sensor. Either way, get it checked out.

 

Thank you for the responses, guys.

I thought it could also be the 02 sensor, but at 14k? I guess i'm also a bit swayed on my experience with a "bad" 02 sensor on my old Maxima - it diagnosed as a bad sensor but was due to the gas (could only get regular during the whole Hurricane evac here in Houston a couple years back). Put premium back on and the light didn't come back.

In any case, i'll have it checked out. Do you guys recommend having it done at Carmax (with their 30 day warranty, or 5 day return policy on the vehicle itself, which ends today) or directly at the dealership? (Still have the remaining warranty from Infiniti left on the vehicle).

Thanks.

 

take it to infiniti, you'll get a loaner and maybe less BS

 

+1 - and I recommend NW Infiniti, although that may be too far for you. West service seems to be okay too.

And welcome Mike!

 

thanks!

Okay, got an update. It's the Cat Converter. They're replacing it but it will take a day or two to get the part in.

Why would a cat fail at just 14k? Any ideas? Could the previous owner have done something really bad that could trigger it?

Thanks!

 

cars are very finnicky...however, i also think that a cat failing at 14k is ridiculous...

The only thing I can think of is if the previous owner had replaced the cats with high flow cats and then before returning the car replacing it with the stock cats...although I doubt this could have caused problems like this if everything was done properly