P0172 means system too rich (bank 1). Too much fuel (or too little air) on bank 1. You'll often smell fuel, see black exhaust smoke, and watch fuel economy ta
Drive gently and get it diagnosed within days.
Too much fuel (or too little air) on bank 1. You'll often smell fuel, see black exhaust smoke, and watch fuel economy tank.
Drips fuel even when closed.
Over-reports airflow.
Pressure too high.
Starves the engine of air.
Bad feedback loop.
Typically $100–$600
Air filter under $30 DIY; injector service typically $150–$400; fuel pressure regulator typically $200–$400. Estimates vary by vehicle. Costs are estimates and vary by vehicle, location, and shop.
Safe to drive, but rich running washes oil off cylinder walls and can kill the converter. Fix within a week.
Typically $100–$600. Air filter under $30 DIY; injector service typically $150–$400; fuel pressure regulator typically $200–$400. Estimates vary by vehicle.
Drive gently and get it diagnosed within days.
The most common cause is leaking fuel injector. Drips fuel even when closed.