Hello guys, I have a 2005 Infiniti G35 Coupe. I had the OBDII code P1273 which means lean fuel mixture bank 1 sensor 1 a while ago. The bank 1 sensor 1 heated a/f mixture sensor is replaced. This did not fix the problem, then I had a smoke test and the plenum spacer was leaking. The plenum gaskets were replaced and the car was running fine for 2 months. Right now the service engine soon light came back on with the same code! The car has a cold air intake, plenum spacer, no cats, and a hks hipower ti exhaust. My mechanic says that I need to replace all sensors but doesn't make any sense! And I don't want to spend 500-600 bucks for a car I am going to sell in 2 weeks I read on the forums that the following things can cause this and I don't know where to start:

- Plenum bolts are loose,
- Bad or dirty MAF sensor,
- Bad fuel pump,
- Replacing all the sensors (Doesn't make any sense?? Each sensor has its own code)

I really need your help with this! Appreciate it!

 

By "no cats" I assume you mean stock cats, and no HFCs or test pipes?

 

Sorry, I mean test pipes

 

Getting an Osiris tune will correct your lean condition, it worked for me. If you don't have the $500 for the tune put your OE cats back on which will also fix the issue you're having....Gary

 

Thank you for your reply Gary. Yes I do not want to spend that much, as I said I am selling the car. Unfortunately I bought the car without the OE cats. I am not sure if the car has o2 extenders installed but do you think installing the extenders may fix the problem?

 

You could try extenders if they don't already have them. How do you buy a car and not have some type of inspection when ownership is changed, I thought that was nation wide? Your car should have had OE cats when you bought it or at least have them available....
Gary

 

I have no idea how that happened. I got it from a dealer and he did all the paperwork. I learned that the car had test pipes when I needed to get the flexible mufflers changed and went down the car You are right I should have had them So you say the only easy way is to try the extenders right?

 

..... Umm yeah you gotta change your test pipes and get GOOD test pipes, I had the same problem I ordered some eBay test pipes that were cheap and my lights came on (p1273) but as soon as I got the Megan test pipes on the light went away, in order to pass inspection you will have to change them anyway

 

As far as I know, the ones I have are Injen Test Pipes. Anyways, thanks for the information guys. I will check if there are extenders installed. BTW I donno if its right to send the link here but, anyone is interested

http://houston.craigslist.org/cto/2872729055.html

Price is negotiable.

 

Changing your test pipes or adding a bung for your O2 sensors is not going to correct your problem. You have test pipes without a tune, you are going to run lean, that's an issue that could damage your engine. Adding those O2 bungs may prevent you from throwing codes, but that's treating the symptom and not the problem. Get a tune if you want to prevent damage.

 

I'd go back to the dealer you bought the car from and ask them, "Why did you sell me a car that had the OE cats removed which is illegal?" That wouldn't fly here in CA., it would have to pass smog to change ownership. Can't believe Texas is too much different....
Gary

 

Some of the bigger cities such as Houston and Dallas have adopted a clean air type act. However, there are still a overwhelming majority of counties that don't do emissions testing. I just recently passed my inspection and I am modded and running ART pipes. They didn't care.

-Sean

lulz