This code indicates that the air/fuel mixture in the engine's cylinders on Bank 1 is too lean. "Lean" means there's too much air and not enough fuel.
What this means in practice: Your engine is getting less fuel than it needs for optimal combustion. This can lead to various problems, including:
* Reduced power: The engine might feel sluggish or lack power.
* Rough idle: The engine may idle unevenly or stall.
* Poor fuel economy: You'll likely get worse gas mileage.
* Damage to the catalytic converter: A prolonged lean condition can overheat and damage the catalytic converter.
* Check Engine light: Obviously, the check engine light will illuminate.
Possible causes for P0171 on a Chevy Tahoe:
* Vacuum leaks: A leak in the intake manifold, vacuum hoses, or other parts of the intake system will allow excess air to enter the engine, making the mixture lean. This is a very common cause.
* Faulty mass airflow sensor (MAF sensor): The MAF sensor measures the amount of air entering the engine. A faulty sensor can provide inaccurate readings, leading to a lean condition.
* Faulty fuel injectors: A clogged or malfunctioning fuel injector can prevent sufficient fuel from being delivered to the cylinders.
* Fuel pump issues: A weak or failing fuel pump may not be able to supply enough fuel to the engine.
* Fuel pressure regulator problems: The fuel pressure regulator might be faulty, not maintaining the correct fuel pressure.
* Oxygen sensor problems: While less likely to be the *primary* cause of P0171, a faulty oxygen sensor (O2 sensor) can contribute to the problem by providing inaccurate feedback to the engine control unit (ECU).
* Problems with the PCV (Positive Crankcase Ventilation) system: A clogged or damaged PCV system can cause excess air to enter the intake.
Troubleshooting:
It's crucial to have a qualified mechanic diagnose the specific cause of the P0171 code on your Tahoe. Simply throwing parts at it can be expensive and ineffective. A mechanic will likely use a diagnostic scanner to read the code and assess other data from the vehicle's computer, along with visual inspections and tests to pinpoint the problem. They will likely start by checking for vacuum leaks, inspecting the MAF sensor, and then moving on to other potential issues as needed.
