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P0171 is a diagnostic trouble code (DTC) for "System Too Lean (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. 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.
System Too Lean (Bank 1)
The P0171 OBD-II code means that, on the first bank of the engine, the fuel system is running weak or a vacuum leak exists near this side of the engine. A lean condition occurs when the engine either receives too little fuel or too much air.
Causes of the P0171 code may include:
Symptoms of the P0171 code may include:
Assuming that no other trouble codes exist, a mechanic may diagnose the P0171 code by checking the engine for vacuum leaks with a vacuum gauge. A vacuum leak will create a hissing sound usually only audible when the engine is turned off.
The fuel pressure sensor and MAF sensor (mass air flow) will also be checked with a fuel pressure gauge.
In order to maintain a proper air/fuel ratio, the vacuum and fuel pressure of the engine must be within the manufacturer’s specifications. The cause of this trouble code will likely be discovered during one of these two tests.
If the cause of this issue is still not found after the mechanic has performed these two tests, the problem likely lies with a sensor.
The mechanic would then run tests on the mass airflow sensor and the oxygen sensors using the manufacturer’s procedure.
If all of these tests have been performed and no issues are found, the problem is likely the powertrain control module.
A mistake that often occurs is not looking for any technical service bulletins for your specific car model that may be related to this issue.
Although not every trouble code will have a technical service bulletin associated with it, it is always wise to check. They can save you a world of time and effort.
The P0171 code is a serious issue. If a vehicle has this code stored in its powertrain control module, the engine of that vehicle simply will not run well. If the engine does not maintain proper air/fuel ratio, there will be a major waste of fuel and a lack of power while driving. It is a good idea to have this code diagnosed and repaired as soon as possible to have your vehicle running smoothly.
It is unwise to drive a vehicle with this trouble code stored for a long period of time. If an engine runs improperly for a long period of time, further damage may result that could end up being much more costly to the owner of the vehicle.
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 1-800-701-6220.