P0171 means system too lean (bank 1). The engine is getting too much air or too little fuel on bank 1. The computer has maxed out its fuel trim trying to comp
Drive gently and get it diagnosed within days.
The engine is getting too much air or too little fuel on bank 1. The computer has maxed out its fuel trim trying to compensate. Common symptoms: rough idle, hesitation, sometimes stalling.
The #1 cause — cracked hoses, intake gasket, PCV issues.
Under-reports airflow; cleaning often fixes it.
Fuel starvation.
Restricted delivery.
False lean reading.
Typically $50–$600
MAF cleaning is often under $50 DIY; vacuum leak repair typically $100–$400; fuel pump typically $400–$600. Estimates vary by vehicle. Costs are estimates and vary by vehicle, location, and shop.
Safe for short drives, but a lean engine runs hot — prolonged driving risks misfires and converter damage. Fix within days.
Typically $50–$600. MAF cleaning is often under $50 DIY; vacuum leak repair typically $100–$400; fuel pump typically $400–$600. Estimates vary by vehicle.
Drive gently and get it diagnosed within days.
The most common cause is vacuum leak. The #1 cause — cracked hoses, intake gasket, PCV issues.