Question about Volkswagen Cars & Trucks
Code p 0171 refers to system too lean bank 1=== causes ---intake /exhaust leak---AIR system--MAF/VAF sensor---fuel pressure/pump---injector/s---heated oxygen (HO2S) sensor
the HO2S is the unit that controls the mixture and is located in the exhaust manifold / pipe before the cat converter
the oxygen (O2S) is just like a final trim and reads the cat converter operation and is located after the cat converter
bank one is closest to the fire wall
Posted on Dec 24, 2016
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Posted on Jan 02, 2017
Here are some possible causes, I would start with anything related to replacing the intake.
Air leaks in intake manifold, exhaust pipes or exhaust manifold
Fuel control sensor is out of calibration
Low fuel pressure (fuel filter clogged, pressure regulator failure)
One or more injectors restricted or pressure regulator has failed
O2 sensors contaminated, deteriorated or has failed
Vacuum hose is disconnected, broken, leaking or loose
Posted on Jan 28, 2009
oxygen sensor, vacuum leak, and yes it could most definitly be if you swaped the wires of the firing order accidently you will get a code p0171 Check the tubing going from the air filter to the intake manifold to see if it has come loose. This might account for extra air going into the intake manifold than the computer is aware of. Otherwise it may be due to a faulty(or dirty) MAP/MAF sensor. Another possible cause is from low fuel pressure due to restricted fuel lines or a bad fuel pump.
Posted on Jul 28, 2009
check the mass air flow sensor there maybe dirt on the filiment inside the sensor causing false readings. cleaning or replacing it may make the codes go away.
Posted on Nov 18, 2009
Hello! I am sending two diagrams...#1 is O2 sensor location and #2 is a vacuum diagram...Before you spend a lot of money replacing O2 sensors lets eliminate other possible causes of heater circuit failure...O2's have heater circuits to bring them up to high temperature quickly so the computer (PCM) will have close control...I would suspect poor grounding, or connector contact corrosion...If you have an ohm meter...Set it on the X10 scale...Measure from center of the negative battery post to the chassis (bare metal)...And then to the engine block...Record both readings...Radio Shack sells a no-touch contact cleaner called DEOXIT...Spray a very small amount on all O2 connectors (male and female)...Oxidation is chemically removed...Re-connect...
Check all vacuum lines for broken, cracked, loose or collapsed...Send results....Guru...Saailer
Posted on Sep 10, 2010
SOURCE: check engine light code P0171
That code is a good O2 sensor reporting a lean condition. Lazy people and part stored just say it is the O2 sensor because they don't know how to fix it. Bank 1 is the side of the engine with the number one cylinder. That bank has a lean condition meaning it doesn't have enough fuel for the given amount of air. Since this is only affecting one side of the engine, that narrows down possible causes. Possible causes would a leaking intake gasket or a broken vacuum hose on that side. Since both sides get fuel from the same pump and rail, this wouldn't be a fuel pump or regulator issue. It can, however, be an indication of a bad fuel injector on that side of the engine. The MAP sensor also couldn't cause this code because, just like the fuel pump, that MAP sensor works for both sides of the engine and the code is only for one side. I would drive it for a couple more days to see if you get any additional codes that could help point you towards the actual problem. In the meantime, I would check for vacuum leaks (look at the rubber hoses and listen for high pitch hissing or sucking sounds.)
Posted on Mar 03, 2011
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