Accord p0172 code defined p0172 is thrown when the oxygen sensors detect that the air fuel mixture is too rich bank 1 refers to the rich condition being detected on the side of the engine with cylinder 1 a rich condition indicates that the air fuel mixture has too much fuel or not enough air. P0172 honda meaning with the air fuel mixture ratio self learning control the actual mixture ratio can be brought closely to the theoretical mixture ratio based on the mixture ratio feedback signal from the heated oxygen sensors 1. Possible causes of obd code p0172 honda 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. My accord 2004 24 is taking to much gas around 25 went to check code p0172 i replaced the sparks maf filter o2 sensor i noticed that rmp improved it accelerate faster especially while driving in the city after driving 12 km the check engine light it pop up again with same 0172 code