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P171 OBD problem on 2003 VW Jetta 1.8 Turbo ! Whats wrong ?

  • P171 OBD problem on 2003 VW Jetta 1.8 Turbo ! Whats wrong ? you know what can cause that problem ....cant pass smog check !!! please help if you know ...thank you

  • Answer:

    The other answerer is technically correct, but he did not give you any VW specific help. That engine in particular is well known (by vw techs) to have bad vacuum lines, and that code is caused 90% of the time by a leaking hose, there are two main locations on that engine that are subject to leaking. 1. Fuel pressure regulator vacuum line. if you open the hood, remove the plastic covers (the one that has the vw logo on it, and the one surrounding the dipstick) then look at the right hand side of the fuel rail, you will see a small shiny round thing with a black fabric covered tube coming off it, this is a vacuum line, check both ends of this hose for cracking or breakage, if it is broken, or cracked, replace it. perform the same check/replacement for the other location: 2. Secondary air injection valve. Larger shiny round thing located on the opposite side of the engine from the belts, underneath the big rubber air hose coming from the air filter housing. if you find and fix a problem, then go to an autozone to have them clear the code, and then wait a day or two of driving before going to your smog test to allow the car to reset all the parameters, and set readiness code. feel free to email me if you need further help.

VASYA at Yahoo! Answers Visit the source

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P0171 means, System Too Lean. It is referring to the fuel/air mixture and it means that you have too much air in relation to fuel. There are lots of things that can cause this so you need a mechanic. Here are a few:- A vacuum leak at the intake manifold Air leak at the air mass meter Air leak into the crankcase (Make sure dipstick is pushed right in and the oil filler cap is secure) Air leak in the PCV system (Positive Crankcase Ventilation) Low fuel pressure Faulty fuel pressure regulator Faulty engine temp sensor (For the computer, not the gauge) Faulty MAP sensor (Manifold Absolute Pressure) Faulty MAT sensor (Manifold Absolute Temperature) Faulty MAF sensor (Mass Air Flow) Faulty TPS (Throttle Position Sensor) Faulty ECU (Computer) Faulty earth for the injector harness or ECU O2 sensor over trimming Dirty injectors

Jules G

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