Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Fuel Control: Notes
The purpose of the fuel control system is to deliver the correct amount of fuel to the engine under all operating conditions. Fuel is delivered by the fuel injectors which are controlled by the ECM. The main control sensor is the oxygen sensor (O2S) located in the exhaust manifold. Sensor tells the ECM the amount of oxygen in the exhaust gases and the ECM changes the air/fuel ratio to the engine by modifying fuel injector pulse width. Fuel system operates in one of 2 modes: open loop or closed loop.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.