I have 07 g35 coupe 6mt and I recently replaced air filter (~200 miles ago), put heat reflective tape (~200 miles ago) on the stock intake, replace cabin filter (~50 miles) and replace drive betls (~2 miles). And I ended with P0133 code. This is its definition:

Definition: fuel air (AF) sensor 1 circuit slow response

Probable cause:
1. Lean A/F ratio - fuel system faulty
2. Large vacuum leak on engine
3. Faulty MAF sensor
4. Faulty AF sensor

The only 'mistake' I think I could have done was that I started the car without attaching the flat long rectangular intake section (stock intake) after replacing drive belts. I was checking the belts for proper installation. The rest of the intake was properly attached and the plug for MAF sensor was attached too. And after that driving few miles, the SES light came on.

Now I was wondering if that could have caused the light to come on or taping the intake? I had it reset and it hasn't come back on in about 25 miles yet.

Any ideas? I know we have MAF, and two O2 sensors on our cars but where is AF sensor? Whats the worse I will have to do to fix this?

Thanks for tips!

 

What air filter did you use? New K&N filters have been known to throw codes, due to the heavy oiling. Adding heat tape inside the intake just adds another uncertainty issue imo.

Hopefully the reset worked it out.

 

Its an OEM filter. And I only taped the outside. Nothing inside. Its been 50 miles and no SES light yet. Finger crossed.

 

Its been well over 500 miles and the light didn't come back. So now I am quite confident it was only because I started the car without attaching the the long flat rectangular air intake attachment.

So if you anyone else ends up doing what I did, just reset the code and you should be good.

 

Since the "snorkel" only funnels air into the stock air box there's no way it caused a vacuum leak or set off your SES. I don't really have an answer for you on what popped the code, but a vacuum leak usually doesn't go away by itself.

Glad it's fixed and hope it stays away!

 

Maybe you just shocked your G by adding the new filter and slightly cooler air, this was just a fluke and may never happen again....hopefully!
Gary

 

Just an update....the light hasn't been back! Its been 2k miles.

My analysis, it could be what gary c said. New air filter and much cooler air because of heat shield tape caused the sensor to think it was working too slow to keep up or thus "slow response".

The other thing as I mentioned earlier could be funnel because when car is idling with hood open, it is taking in small amounts of air compared to while being driven. The funnel is designed to channel air in efficiently when the car is moving but it doesn't help much when car is stationary. My point being that with the funnel removed, there was a huge hole in the intake box causing increased airflow in. So again it goes back to sensor thinking that it is having "slow response".

 

I have a cold air intake on mine and it throws the same code and I try to clear it and it just comes back on it's a injen cold air intake runs fine but that light stays on and won't go away untill you reset it.... But comes back not long after it's reset any ideas?

 

If it keeps coming back then I would you actually have a problem with the sensor. You would probably have to replace it. I don't have cold air intake in my car so maybe someone who does can let you know whether or not you should be getting that code.

 

I was alway told if the MAS is bad or going out it would run bad and my car runs great no Loss of power at all it's my first G so I dot k ow too much sill tryin to learn guess I'm gonna have to take it to the dealership to get it checked out I also have a popping noise when I turn every now and then and I have no clue what it is everything looks fine under there but then again I may not know what I'm lookin for always been a GM guy until now

 

It could be your AF/O2 sensor as well. Popping noise could be related to compression rod bushings. If you are not under warranty, dealer is going to charge you a lot so you might want to take to another trusted mechanic.