If the fuel pressure is off, atomization doesn’t happen properly and the optimal air/fuel mixture isn’t achieved.

Fuel Pump/Fuel Filter– Today’s modern fuel injected motors need a lot of fuel pressure to atomize the gas properly.

Bad Fuel Injectors– If you have one or more fuel injectors that have gone bad that can certainly cause the air/fuel mixture to go bad.

If it has gone bad, the air fuel mixture will be off and the P0172 code will show.

Mass Air Flow Sensor– The mass air flow sensor calculates the volume of air entering the engine.

The computer will still adjust the air/fuel mixture to compensate. When the oxygen sensor is bad, it can cause a false reading and trigger the code.

Oxygen Sensor– The P0172 codes is thrown when the oxygen sensor(s) do not register the right amount of oxygen in the exhaust.

Here’s a great YouTube video on how to find a vacuum leak. Take a look around and see if you can find the vacuum leak.

Vacuum Leaks– With the Honda Accord, one of the most common cause for the P0172 code to show is a vacuum leak.

Here are the most common causes of P0172: This youtube video is a great resource for diagnosing the P0172 trouble code in your Accord.

Fouled Spark Plugs– The spark plugs can foul if the engine runs very rich for a long enough period of time.

Exhaust Smell/Color– Depending on how rich the motor is running, there could be some exhaust odor or discoloration.

Idle Issues– With the air/fuel mixture altered, the vehicle can idle erratically as the computer compensates to keep the engine running.

Misfire– If the air fuel mixture has gotten too far from factory specs, this can cause the Accord to misfire.

Mileage- may or may not suffer depending on how much the air fuel mixture has changed.

Here are the typical symptoms that something is wrong when you have code P0172. For most people the first sign that anything is wrong at all is the service engine soon light coming on. There aren’t usually any drivability issues associated with P0172. Typically the code will be triggered by a rich condition in the engine. The P0172 code on a Honda Accord will often be thrown if the fuel injection system is not operating properly. This would be the opposite of a lean condition, which’ll throw P0171. Bank 1 refers to the rich condition being detected on the side of the engine with cylinder 1.Ī rich condition indicates that the air fuel mixture has too much fuel or not enough air. P0172 is thrown when the oxygen sensors detect that the air fuel mixture is too rich. It means that the motor is running with a rich condition. It’s not the most complicated OBDII trouble code to diagnose. This code number references a number that is given to you when you plug your car into a OBDII scanner. A common trouble code with the Honda Accord is P0172.

2010 honda accord 3.5 bank 2 convertor