This thread has been going a while, but I had the same symptoms in my 13 G37x. It happened not long after an emergency stop. I realized that my brake lights were staying on. My brake pedal has some play in it. The brake pedal was not returning to the full up position to trip the safety switch, so the car thinks the brakes are being applied, thus not allowing acceleration fully. I am going to post a new thread on if the pedal is adjustable to raise it up some to contact the switch. Currently I put a small shim of sorts on the rubber piece that trips the switch. Has worked fine since.

 

Better late than never...

I took three steps in order to prevent this limp mode from occurring again. I am not 100% certain that these were the ultimate causes but it hasn't happened since so I am assuming one (or all) of these three did the trick.

1. Cleaned the MAF Sensors. Pretty straight forward.

2. Cleaned the throttle bodies. Back sides had a decent amount of buildup but not to the point where I would expect it to cause limp mode.

3. Replaced the intake filters. I have a K&N Typhoon Short Ram setup. Instead of replacing them with the same K&N oiled filters, I got K&N dry cone filters in the same exact size. No oil needed.

Ultimately I think that the oil on the filter was seeping through and coating the MAF sensor causing the limp mode. Perhaps the filters were oiled to liberally last time, but I figured with the dry filter I wouldn't have to worry about that again. The inside tubes of the intakes showed signs of the oil getting sucked through.

After doing this about three weeks ago the car has been running great with no limp mode.

 

Here's hoping you fixed the problem. And thanks for noting your changes. This will certainly help someone in the future.

 

I cleaned my filters, cleaned MAF, checked for vacuum leaks. Codes went away. Then came back so replaced the MAF sensors since that was the only code I had. Replaced them with new MAF sensor. Codes are back and now ABS, BCM issue plus the MIL is on. Light stays on even after engine running. Just dropped off a dealer today, hoping they can fix it.

Current codes: P0101, P010C, P1721, C1130, B2562,

Keep this thread updated when I hear back.

 

Let us know what they find out.

 

I got a call from the dealership today and based on what they told me, I figured the solution to my problem would consist of what they told me. They are going to clean my throttle bodies, replace the air filters (I cleaned them prior to the decision of going to the dealer), replace the MAF sensors and replace the battery terminal. I was aware of the battery terminal, it was beginning to warp. So based on the codes I had, I think I had an electrical problem/insufficient voltage or circuit (at times I could pull off the neg connector without unscrewing the bolt) with the sensors and BCM. I also had never cleaned the TB's. Probably could of done myself but needed to get this issue taken care of immediately. I have a good relationship with my advisor and the dealership, so I am confident they have taken care of my issue. I pick up my G tomorrow. Will keep this thread posted.


***Update 4/11/18
The car drives A TON smoother.....sounds louder in a good way. Very happy with the results, here's to hoping that it resolved all of the issues.