Hello everyone,

This is my first post here but I have been lurking for quite sometime now. I have read and read and read trying to solve the issue of the p1283 SES that has popped up on my newly acquired 2005 g35 sedan. Purchased the car a month ago and on the way back home to Nashville from Atlanta the SES popped on. Was told by the previous owner that the only mods done to the car were a z-tube and coupe midpipe. Sent a text to the guy I bought the car from and of course he has no idea why it would throw a code. Had the code ran it comes back p1283 which is (A/F) sensor 1 (Bank 2) lean shift.

I took the car to my local Nissan dealership and had a good buddy of mine there try to diagnose the issue. No vacuum leaks, o2 sensors are reading within a couple percent of each other, maf is good, ecu was fully updated, and his conclusion is that it might be the fuel pump causing me to run lean. I don't really have the time or extra cash to guess and throw parts into the car so I took it to the Infiniti dealership to see what they would say. After another $125 in diagnostic fees, there diagnoses was that the car has aftermarket catalytic convertors (possibly hi-flow cats) and an aftermarket o2 sensor with a spacer. Said that the car was running extremely lean. The gas mileage is not what I think I should be getting and I the car does have a strong smell of gas while idle. Pretty positive under load I am getting some spark knock which is a major concern for me.

I would greatly appreciate any and all advice that can help me solve this issue. I am currently searching for a stock exhaust to replace the current one and hope that will solve the issue.