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Can bad fuel cause P0171?
Causes of the P0171 code may include: A faulty fuel pressure regulator. A clogged fuel filter.
What causes lean fuel trim?
If the fuel trim readings do not change much, the lean fuel condition is more likely due to a fuel delivery problem (weak fuel pump, restricted fuel filter, dirty fuel injectors or a leaky fuel pressure regulator) than a vacuum leak. The most likely cause would be dirty fuel injectors.
Can a bad O2 sensor cause P0171?
Additional Causes of Code P0171 A plugged Fuel Filter or poorly functioning Fuel Pump can set the P0171 code. The computer hears (accurately) from the Oxygen Sensor that the Fuel Mixture is too lean so the computer keeps increasing the amount of fuel being delivered into the combustion chambers.
What causes a GMC fuel trim system p0171 code?
The P0171 code could also be caused may be caused by one or more of the following: debris on MAF sensor causing an incorrect reading, improper oil level, low or high fuel pressure or Engine Control Temperature (ECT) Sensor reading inaccurate. There is a factory service bulletin for the following GMC models:
What does code p0171-system too lean mean?
Code P0171 – System Too Lean: Symptoms, causes, common problems, diagnostic. The OBDII trouble code P0171 – System Too Lean (Bank 1) means that the engine air-fuel mixture is too lean, or there is too much air and too little fuel.
Where is Bank 1 on a fuel trim system?
Note that “Bank 1” refers to the bank of cylinders that contains cylinder #1, and that “#1 oxygen or air/fuel ratio sensor” refers to the sensor that is located upstream of the catalytic converter on Bank 1.
What does it mean when fuel trim is too lean?
However, in practice, the PCM makes adjustments called “fuel trims” to adjust the fuel mixture several times per second, and when it detects that a lean condition (too much air relative to fuel), exists that it cannot compensate for, it will recognize that it cannot control the air/fuel mixture effectively.