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P0173 is a diagnostic trouble code (DTC) for "Fuel Trim Malfunction (Bank 2)". 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.
P0173 Fuel Trim Malfunction (Bank 2)
Code P0173 is triggered by the engine control module (ECM) when it detects that the air-fuel ratio is too lean or too rich. For most lean and rich conditions, the ECM can compensate for the lack or air or gas entering the engine. However, if the amount of compensation is too much, a P0173 code may set.
Fuel trim is what the ECM implements to adjust the air-fuel ratio of the engine according to changing driver conditions. The air-fuel ratio should stay at, or very near to 14.7:1. It must stay at this range during idling, going down hills, cruising, and at highway speeds.
There are two forms of air-fuel ratio adjustment: short-term and long-term. Short-term fuel trim happens almost instantly, while long-term fuel trim is a gradual adjustment that happens over longer durations in contrast to the instant adjustment provided by short-term fuel trim.
The ECM can only adjust the air-fuel ratio to a certain extent. If the ECM can not compensate for the required adjustment, a P0173 code may set.
Replacing the Mass Air Flow Sensor without cleaning or testing it first
Deeming a component faulty without checking for more common causes, such as vacuum leaks
Not using a scan tool to determine if there is an issue with either the short- or long-term fuel trim
Failing to inspect the wiring of the component thought to be at fault
The life of the catalytic convertor could become shorter because it will have to filter more pollutants in the exhaust gases
Gas consumption will increase
It is suggested to always check the wiring of a component and clean it before deeming it faulty. It’s also a good idea to check the intake system and vacuum lines for leaks.
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.