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: Description
The purpose of the air injection system is to reduce exhaust emissions by oxidizing hydrocarbons (HC) and carbon monoxide (CO) during cold engine operation.
The system is composed of air suction valve(s), thermosensor (used on all Calif. models and Federal FWD models), solenoid valve, check valve, thermostatic air cleaner (TAC), silencer(s), various hoses and tubing and the electronic control module (ECM). Depending on model and application, secondary (fresh) air is supplied to exhaust ports on either one (Calif.) or both (Federal) cylinder banks.
There are 2 types of air suction valves used with the air injection system. On all California models and Federal 2WD models, air suction valve(s) include a cut-off valve. Federal 4WD models use air suction valves without cut-off valve. See Fig 1 and Fig 2
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.
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