Fix code P0171 System too lean (Bank 1)
If you have a P0171 System too lean (Bank 1) trouble code, read this to understand what it means
Lean codes are incredibly difficult to diagnose. And it’s one trouble code where you don’t want to start throwing parts at the problem. The guys at the parts store will tell you to replace the Oxygen sensor. Nice guess, but probably wrong. They’re assuming that the fuel mixture is correct but the sensor is reporting it wrong. Oxygen sensors DO wear out. But what if the mixture really IS lean? Can it be lean on only one bank (of a V-6 or V-8) engine? You bet. This kind of code screams out for a little diagnostic work. First, check all the vacuum hoses for cracks and correct placement. Next, spray carburetor cleaner around the intake manifold gasket and listen for an increase in engine RPM. Any increase after spraying indicates a vacuum leak.
The Bank 1 indication tells you that the problem is located on the cylinder bank that contains the #1 plug. That varies by make and engine style, so make sure you check the shop manual.
© 2012 Rick MuscoplatPosted on by Rick Muscoplat