please help not able to find error

I don't know exactly what the challenge asks you to do, but looking at your code I've spotted some errors. I'm gonna use your code and comment how the line probably should be written. Take a look:

class RaceCar:
    laps=0
    def __init__(self,color,fuel_remaining,**kwargs):
        self.color = color
        self.fuel_remaining = fuel_remaining
        for key,value in kwargs.items():
            setattr(self,key,value)

    def run_lap(self,length,fuel_remaining):
        laps=laps+1  # it should be self.laps = self.laps + 1. "laps" is a class attribute, so when the instance is created it will be an instance attribute as well.
        self.fuel_remaining=self_remaining  # You probably wanted to write "fuel_remaining" instead of self_remaining.
        self.length=length  # You don't need this line. You can delete it. Here you are defining an instance attribute outside of __init__.  You should define instance attributes inside of __init__. 
        return self.fuel_remaining-(length*0.125)

Again, I'm gonna rewrite below the comments:

1. it should be self.laps = self.laps + 1. "laps" is a class attribute, so when the instance is created it will be an instance attribute as well.
2. You probably wanted to write "fuel_remaining" instead of self_remaining.
3. ou don't need this line. You can delete it. Here you are defining an instance attribute outside of init. You should define instance attributes inside of init.

If you still have questions, feel free to ask.

EDIT: I just saw KRIS NIKOLAISEN answer to you. He knows what challenge you're in, so he's answer should be more specific. I just commented line by line on your code based on what I find you probably wanted to write.

So first things first, be careful because you're doing to much here, the challenge only asks for the new method to take length as an additional argument, but you've also added in fuel_remaining.

class RaceCar:
    laps = 0

    def __init__(self, color, fuel_remaining, **kwargs):
        self.color = color
        self.fuel_remaining = fuel_remaining
        for key, value in kwargs.items():
            setattr(self, key, value)

    def run_lap(self, length, fuel_remaining): # fuel_remaining is unnecessary, you already defined it in def__init__ 
        laps = laps + 1  # you're not telling the method to refer to the laps attribute 
        self.fuel_remaining = self_remaining # what is self_remaining?
        self.length = length 
        return self.fuel_remaining - (length*0.125) # you don't need to return anything here, but also, see how you're calling fuel_remaining from self.fuel_remaining? It's not using the self.fuel_remaining = self_remaining you defined here a couple lines up, which isn't doing anything other than redefining the variable you'd already set for no reason.   

Remember challenge 2 asks only for the length argument to be added as a variable of the method, and it doesn't need to return anything, it's just changing the already stored values for fuel_remaining and the laps attribute. Like myself and I'd wager many new programmers you're just overthinking the problem, run_lap for task 2 only needs 2 lines of code to achieve what the task desires. Mull it over and I think you can get it, i'll check back in later.