P1273 Horror Story
 

Hey guys,

I have an 05 AT G35 coupe with about 133K miles. So I've been dealing with this code for a long time now and I had no choice but to try to get it fixed since my inspection was coming up. Managed to get my inspection done yesterday and passed BUT the code still comes back. Here's what I've done.

I replaced the following parts;

Bank 1 Sensor 1 Oxygen Sensor

I actually got it replaced twice. The first time it was a Bosch, code came back up after 15 miles. Decided to ignore the code due to financial reasons and because I had a year left until inspection. So a few months ago, I replaced it with a Denso because I've read Bosch may not work.

Cats

Bought some cats and got them replaced. My mechanic was the one told me that that was the problem, but after 20 miles, the code comes back again.

With these 2 replacements, the code comes back after 15-20 miles. I've done the ECU reset with the pedal and it always came back.

After doing some more research, I decided to do the following;

• Change the spark plugs
• Changed PCV valve
• Changed Air filter
• Cleaned the MAF sensor with CRC.

I also disconnected the battery during this for about 2 hours. Once I started the car, the car performed like I just got it from the dealer :) After about 20 minutes of driving though, it went back to its sluggish performance.

Oddly enough, the code didn't come back until about 150 miles. I reset the code, did the drive cycle the next morning and got my inspection before the light came back. Does anyone have any idea why the code comes back after 150 miles as opposed to the 20 originally? It feels like I'm getting close to fixing it but this is driving me nuts lol. As far as I know, I have no vacuum or exhaust leaks. My fuel gage is off though, it's been that way for awhile. My tiptronic doesn't work in regards to downshifting and sometime's it doesn't work at all. Doubt these have anything to do with it but just putting it out there. Any help is appreciated guys.

Sometimes an hour diagnostic fee at the dealership is the best choice.

About the shifting however, on the front of the engine at the top of the timing cover are a couple of ground wires bolted to the cover, clean them up with a brush and use anti-oxidation grease when reassembling, there's also a larger gauge wire jumper from the passenger side of the block to the chassis directly below the coolant reservior (just remove the single bolt for the reservior and lift it up no need to remove the hose), also the primary wire from the negative post of the battery to the chassis.

Clean those up with a brush, de-ox everything (not that damnable spray battery terminal protectant, actual OXIDATION INHIBITING GREASE), reassemble. This usually fixes the shift issues.