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.
Air Injection System: Operation
The air injection system is used to improve catalyst operation when the engine is warming up. Air is injected only if engine coolant temperature is below 108°F (42°C), oil temperature is above 61°F (18°C) and the oxygen sensor is not operating. When these conditions are present, the air injection relay provides power to the air pump clutch and the switch-over valve.
When the switch-over valve is activated, it provides vacuum to open the air injection shut-off valve, allowing air from the pump to pass through the check valve into the exhaust manifold.
Use the Manual With the Right Hardware
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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.