P0172 OBD II Trouble Code System Too Rich (Bank 1)

Symptoms of P0172 OBD II Trouble Code

  • The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters can cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
  • There could be a vacuum leak.
  • There could be a fuel pressure or delivery problem

Common Causes of P0172 OBD II Trouble Code

  • Inspect all vacuum and PCV hoses, replace if necessary
  • Cleanthe MAF sensor. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
  • Inspect fuel lines for cracks, leaks, or pinches
  • Check the fuel pressure at the fuel rail
  • Check the fuel injectors, they may be dirty. Use fuel injector cleaner or get them professionally cleaned/replaced.
  • Check for an exhaust leak before the first oxygen sensor (this is unlikely to cause the problem, but it is possible)