OBD Diagnostics for Engine Air–Fuel Ratio Optimization

The air–fuel ratio (AFR) determines how efficiently an engine burns fuel. Even small imbalances can lead to power loss, high emissions, or engine damage. OBD air–fuel ratio diagnostics provide real-time insight into combustion quality and ECU corrections.

Understanding Air–Fuel Ratio

Ideal AFR Values

• Gasoline engines: approximately 14.7:1

• Rich mixtures improve power

• Lean mixtures improve fuel economy

Why AFR Changes

• Sensor feedback

• Engine load

• Temperature conditions

How OBD Monitors AFR

Key Data Sources

• Oxygen sensors

• Fuel trims

• Injector pulse width

• Engine load

Problems Detected

• Lean or rich conditions

• Sensor aging

• Injector imbalance

Benefits of AFR Diagnostics

• Improved fuel economy

• Reduced emissions

• Smoother engine operation

• Early fault detection

Conclusion

OBD AFR diagnostics help maintain ideal combustion for long-term engine health.