Today’s engine management systems rely on many different sensor inputs to regulate fuel economy, performance and emissions.
Symptom: Poor Fuel Economy
Probable Causes: Fuel Rich Codes (P0172 and/or P0175)
With the price of gasoline, you don’t want to ignore this kind of problem for long. When fuel economy is down, you may find any number of codes: • P0172 and/or P0175 are rich codes, and indicate a general rich air/fuel condition. The underlying cause may be anything that increases fuel delivery, such as excessive fuel pressure, a defective fuel pressure regulator, plugged return line, or leaky injectors. Decreased airflow from a dirty air filter or restricted air intake misleads the mass airflow sensor or engine management system into believing the engine is using more air or is under more load than actual.