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P0172 is a diagnostic trouble code (DTC) for "System Too Rich (Bank 1)". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic for $79.99. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.
P0172 is a trouble code that is set when the ECU senses that there may be too much gasoline present in the air-fuel mixture of the engine.
A proper air-fuel ratio of about 14.7:1 is vital to obtain maximum engine power and fuel economy.
P0172 indicates that there is too much gasoline being detected in the exhaust gases exiting the combustion chamber. The ECU uses a number of instruments, such as the mass air flow sensor (MAF), oxygen sensors, and manifold absolute pressure (MAP) to monitor the air-fuel ratio of the engine.
Most routinely, the air-fuel ratio will be measured through the oxygen sensors calculating the amount of oxygen and carbon monoxide present in exhaust gases. The best air-fuel ratio modernly known to man is 14.7:1. This particular ratio was chosen because it was discovered to have the highest power output but lowest fuel consumption rate.
The ECU has the ability to slightly adjust the air-fuel ratio if it is rich. However, if the margin of compensation is too large, then a P0172 code will likely set. The term “rich” in this case means that there is too much gasoline and not enough oxygen detected in the air-fuel ratio of the engine.
A technician may not inspect the coolant temperature sensor and cooling system. When the engine is cold, more fuel is added to help warm it up to a desirable temperature. If the coolant temperature sensor is not sending the proper signal there is a possibility that the engine ECU may assume that it is always running cold.
The car may not be able to pass a state vehicle inspection because of the P0172 code setting the Check Engine Light.
If the the air-fuel ratio is rich enough, a black smog will come out of the exhaust, which is harmful to the environment.
It is highly recommended to check the condition of the spark plugs and the operation of the coolant temperature sensor.
YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.