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P0171 (2) Chevrolet Uplander I

Testing & Diagnostics ~233 words
  1. Allow the engine to reach operating temperature. With the engine running, observe the Long Term FT parameter with a scan tool. The value should be less than approximately 19.5 percent with the engine running at operating temperature.
  2. If the value is not less than 19.5 percent, inspect for the following: With the ignition ON and the engine OFF, observe the manifold absolute pressure (MAP) sensor parameter. The MAP sensor pressure should be within the range specified for your altitude. Refer to «Altitude vs Barometric Pressure»(ref-241686-S13322339112006081100000) . If the MAP sensor does not indicate the correct barometric pressure, refer to «DTC P0106, P0107 or P0108»(ref-241735-S14863720202006081100000) .
  3. Vacuum hoses for splits, kinks and proper connections
  4. Sufficient fuel in the tank
  5. Low fuel pressure
  6. Fuel contamination
  7. Properly functioning fuel injectors
  8. Missing, loose or leaking exhaust components from the HO2S forward
  9. Vacuum leaks at the intake manifold, the throttle body and the injector O-rings
  10. The air induction system and the air intake ducts for leaks or for a missing air filter element
  11. Evaporative canister purge lines plugged or obstructed
  12. The crankcase ventilation system for leaks
  13. The HO2S for proper installation and for electrical wires or connectors that may have contacted the exhaust system
  14. The HO2S signal circuit open, shorted to ground or shorted to the low reference circuit
  15. The HO2S sensor 1 low signal circuit for an open circuit or high resistance
  16. Malfunctioning engine components

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