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16556/P0172 - System Too Rich, Bank 1

Possible Symptoms

  • Irregular behavior

Possible Causes

  • Fuel system
  • Excessive fuel pressure
  • Leaking or contaminated fuel injectors
  • Leaking fuel pressure regulator
  • Low fuel pressure or running out of fuel
  • Vapor recovery system
  • Air leaks after the MAF
  • Vacuum leaks
  • Improper seated engine oil dipstick
  • Stuck EGR valve
  • Oil overfill
  • Cam timing
  • Cylinder compression
  • Exhaust leaks before or near HO2Ss.

Special Notes

Fuel Trim Info

  • For the Tiguan with the 2.0T DGUE engine that has one or more of the following fault codes, please see TSB 054615 for possible ECM update and hardware update.