P0171 System too lean (Bank 1)
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.
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© 2012 Rick Muscoplat
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I am trying to fix 2005 chevy malibu, 2.2L engine, base model. I am getting P0101, P0300, P0068, and P0171 diagnostic codes. I have changed the sparkplugs, put in new gappless plugs. I have replaced the coil pack with a new one; I am still getting the codes and noticed the engine has a degraded performance and is using more fuel. Should I pull those sparkplugs and but in gapped ones? I have pulled and cleaned the air mass sensor, should I replace the map sensor? I saw a filament piece in the sensor that looks broken.
I don’t understand your logic at all. Why replace a coil pack when the P0300 code is for multiple misfires? Also, you’ve got a lean misfire code and a MAF low input code.
Rip out those gapless plugs. They are know to misfire. Replace with FACTORY plugs–AC Delco.
Next, clean the MAF or replace it. Then, check for vacuum leaks.
A lean condition means too much air is getting in and combustion can’t complete. So you get misfire codes. Since they’re not on a single cylinder (if it was you’d get a misfire code for that cylinder), you most likely have a fuel or air mixture problem. A lean condition would also cause low power and bad fuel economy.
GM MAF sensors have a high failure rate.
Also, get yourself a scan tool with live data and start reading the data stream to see what’s going on. You’ve already wasted more than the cost of the scan tool in wasted parts.
Love it! This code can be a hard code to diagnose at times.
2007 Pontiac g5 is reading p0171 bank 1 and ideas on what I could do?
Look for a vacuum leak
Cant see any visible leaks. Any easy ways to find a vacuum leak
Start engine and spray all vacuum hoses and intake manifold with carb cleaner. If it sucks it in, there’s your leak. Some people use a spray water bottle too–just don’t spray too much water on a single hose.