Lean doesn't mean "lack of fuel" in the case of fuel injected engine computers
O2 sensors report only oxygen in exhaust not fuel
If a cylinder misfire then no oxygen was used up so all that oxygen goes into the exhaust to the O2
Computer response to O2s high oxygen by adding more fuel to that bank of the engine
Which in itself could cause misfire if a spark plug was weak
Old O2 does False Lean, and if there are two O2 sensors, on a V6 or V8, and only one is showing lean, then replacing BOTH upstream O2s would be first step, unless you have a steady misfire on that bank with the lean code
Computer has no comparison for O2s, they are "the word of God" as far as computer is concerned, so any O2 related codes ASSUME O2 is in PERFECT working order as far as computer is concerned
Which is why changing the O2, even swapping it around with another O2, is a good first thing to do with just the one code
Computer programmers have a long standing saying, since the first computers, lol, "Garbage in = Garbage out" meaning the result is totally reliant on the input
Most, if not all, computer "mistakes" come from bad "input"
O2 sensors report only oxygen in exhaust not fuel
If a cylinder misfire then no oxygen was used up so all that oxygen goes into the exhaust to the O2
Computer response to O2s high oxygen by adding more fuel to that bank of the engine
Which in itself could cause misfire if a spark plug was weak
Old O2 does False Lean, and if there are two O2 sensors, on a V6 or V8, and only one is showing lean, then replacing BOTH upstream O2s would be first step, unless you have a steady misfire on that bank with the lean code
Computer has no comparison for O2s, they are "the word of God" as far as computer is concerned, so any O2 related codes ASSUME O2 is in PERFECT working order as far as computer is concerned
Which is why changing the O2, even swapping it around with another O2, is a good first thing to do with just the one code
Computer programmers have a long standing saying, since the first computers, lol, "Garbage in = Garbage out" meaning the result is totally reliant on the input
Most, if not all, computer "mistakes" come from bad "input"