new guy here, i got a code 171 and 174

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by fnoblitt, Nov 11, 2011.

  1. fnoblitt

    fnoblitt New Member

    my 2000 silverado has been a little slow to start up latey. check engine light came on today. has a code 0171 and 0174, i looked them up and it's a lean right and left bank. i'm not that great on diagnosing problems so i did what i knew. i changed the fuel filter(was very dirty), cleaned the map sensor screen(just a little dusty), cleaned the throttle body, and washed& dryed the reuseable air filter(very dirty). changed the oil and filter while i was at it. cleared the codes and drove the truck. the check engine light came on again. so now what might it be? i had the fuel pump replaced about 3 months ago.when it was taking a while to start.
     
  2. 99'HEARTBEAT

    99'HEARTBEAT Epic Member Staff Member 5+ Years ROTM Winner 1000 Posts Platinum Contributor

    Trouble Codes P0171 and P0174 are telling you there's an Issue(Running Lean)Check for a Vacuum Leak and then if O.K....Check the 02 Sensor's before the Cats....
     
  3. fnoblitt

    fnoblitt New Member

    i replaced all 4 o2 sensors about 6 months ago when i had a calitic code. could these go bad or get dirty this soon ?
     
  4. 99'HEARTBEAT

    99'HEARTBEAT Epic Member Staff Member 5+ Years ROTM Winner 1000 Posts Platinum Contributor

    I would Double Check the Connections, also what Brand of 02 Sensor's did you Install, also have you Checked the Fuel Pressure??
     
  5. fnoblitt

    fnoblitt New Member

    i got them from rock auto,made overseas,can't remember the brand. i'm going outside now to pull them, and see what they look like
     
  6. 2COR517

    2COR517 Epic Member 5+ Years 1000 Posts

    Those codes and your driving symptoms are classic for low fuel pressure. Get a gauge and test it.
     
  7. fnoblitt

    fnoblitt New Member

    i've never done that before. is it a simple procedure to do ? if it is, i'll go down to autozone and see if they have a gauge that will work on my truck
     
  8. Aftahoe

    Aftahoe New Member

    Hello. I have a similar question. I have a 2001 Tahoe with the 5.3 engine. I had a leaky fuel pressure regulator or that was giving me a P 300 code. While replacing that, I checked my fuel pressure and it was showing 48psi. I replace the fuel pump and the filter. Shortly after start up, I was showing a P171 and 174 code. Does anyone have any suggestions? I would certainly appreciate any help.
     
  9. xPosTech

    xPosTech Epic Member 5+ Years 1000 Posts

    You'll have much better results if you start a new thread. This one is 4 years old.

    For your problem - 0171 and 0174 both basicly say that the mixture is too lean in bank 1 and bank 2. Since it's both banks you probably have a vacuum leak in the intake system. It might be a broken vacuum line, intake manifold gasket or possibly low fuel pressure.

    Ted
     
  10. 99'HEARTBEAT

    99'HEARTBEAT Epic Member Staff Member 5+ Years ROTM Winner 1000 Posts Platinum Contributor

    Ted....Just a Heads-up the Member has Started a New Thread.....I was just getting ready to Remove his Reply Above in this Thread...when you Replied......:)
     

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