Limp Mode

[roggybear]

I have a 2003 350z that goes into fail safe mode after sitting overnight. The next morning after sitting all night it will not idle. After warming the engine to operating temp and performing the idle re-learn it seems to run fine. The next morning I am back in fail-safe mode. It does throw 2 codes- knock sensor and o2 sensor. Changed both but problems and codes still appear. I have no idea and neither does the dealer. Any help would be greatly appreciated.

[RicerX]

Welcome to NICO!

Has this happened while having the same tank of gas? Sounds almost like you have condensation in your fuel lines or something to that effect. Poor fuel or contaminants in the fuel can possibly trigger the knock sensor, and could lead to an o2 sensor if it's not burning fuel correctly.

I could be totally off on this. Hopefully someone else can chime in with more ideas.