These alphanumeric codes, when retrieved from a vehicle’s onboard diagnostic system, indicate lean fuel trim conditions. Specifically, P0171 signifies that the engine’s air-fuel mixture is too lean on Bank 1, while P0174 denotes the same condition but on Bank 2. This means the engine is receiving too much air or not enough fuel. A common example would be a vehicle experiencing rough idling or decreased fuel economy coupled with the presence of these diagnostic trouble codes.
Addressing these codes promptly is important for maintaining optimal engine performance and preventing potential damage. Extended operation with a lean condition can lead to overheating, catalytic converter failure, and ultimately, more costly repairs. Historically, these codes were less common in older vehicles due to simpler engine management systems, but they are now prevalent in modern vehicles with sophisticated emission controls and fuel injection systems.
