Intermittent misfire and lean fuel?

[joshua]

I have an 09 impala ls. The check engine light came on the other day and I had the auto store run my codes. He said it’s an intermittent misfire and lean fuel. Which I assume go hand n hand with each other.

What could be causing my fuel to lean out and have a misfire?

I do have an exhaust leak but I’m not sure where, I haven’t had a chance to look since the weather up here hasn’t been good enough to dry out my muddy driveway.. Could an exhaust leak cause this? Or what could be the cause?

Topic

[Richard Kirshy]

An exhaust leak will allow fresh air to enter the system on the negative pressure side of an exhaust event, this will cause an oxygen sensor to produce a lean reading. … This will cause the exhaust system to test lean as tested by the O2 sensors.
Other possible causes:
Vacuum leak.
Faulty fuel pump.
Faulty fuel pressure regulator.
Faulty injector(s).
Faulty mass air flow sensor.
Faulty oxygen sensor(s)
Clogged fuel filter.

[Tim Rowe]

Do you know what cylinder is misfiring? If the exhaust leak is bad enough, it could definitely cause a problem? Does the exhaust smell rich? How about fuel mileage? Good luck!

[Author]

Replies