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.
280 Models
The system is designed to inject air into the exhaust ports during a specified period of engine warm-up operation. The oxygen sensor detects the additional oxygen in the exhaust and richens the air/fuel mixture slightly, resulting in smooth operation.
When coolant is below 62°F (17°C), the first thermal valve is closed and no vacuum reaches the diverter valve. Air is vented to atmosphere. When the first valve opens, vacuum passes through to open the diverter valve and direct air to the cylinder head. When the second thermal valve opens at 122°F (50°C), the vacuum is bled to atmosphere at the air intake. The diverter valve once again vents air pressure.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.