Where is the secondary air valve located at?
The secondary air valve is a component of the emissions system that feeds fresh air into the exhaust. Its exact location depends on the vehicle and whether it uses a secondary air injection (SAI) system or a carburetor-based setup. In most modern cars, you’ll find it in the engine bay, near the exhaust manifold or close to the intake/throttle body.
This article explains the common placements of the secondary air valve and how to identify it on different engines.
Overview: what you’re looking for
The secondary air valve is part of the emissions control system that meters air into the exhaust to help reduce pollutants during cold starts. In modern fuel-injected engines, it is typically a small solenoid or vacuum-operated valve connected to hoses that run between the air pump, intake manifold, and exhaust manifold. The exact spot varies by make and model.
Below are the most common locations you’ll encounter, along with guidance on how to locate the valve on your particular vehicle.
Common locations for the secondary air injection valve in modern cars include:
- On or near the exhaust manifold or cylinder head, where the valve can direct air into the exhaust flow (sometimes mounted directly to the manifold or to the nearby exhaust pipe).
- Near the air pump (smog pump) assembly, with hoses and an electrical connector routing air into the exhaust lines.
- On the intake manifold or throttle body area, typically as a small solenoid valve with an electrical connector and several vacuum hoses.
- In some models, tucked behind the engine or along the firewall on the driver or passenger side, inside the engine bay.
Because placements vary widely by make and model, always check your vehicle’s service manual or a factory parts diagram to confirm the exact location for your car.
How to identify the valve on your vehicle
Use these steps to confirm the valve’s location on your specific vehicle:
- Check the vehicle’s service manual or a dealership diagram for the secondary air injection system and valve location by VIN.
- Look for a small electronic valve with a two- to three-pin electrical connector, often labeled AIR, SAI, or similar terms, mounted near the intake manifold, throttle body, or along a hose run toward the exhaust.
- Trace lines from the air pump (if equipped) toward the exhaust manifold; the valve is usually along that line, sometimes with a check valve in the vicinity.
- Inspect for vacuum hoses coming from the intake manifold to a valve or solenoid; this valve typically governs air routing during cold starts.
If you still can’t locate it, ask a technician or use an online parts diagram tool with your vehicle’s exact make, model, year, and engine code.
Carburetor-based secondary air valve
In older or carbureted engines, the term “secondary air valve” often refers to a mechanical or vacuum-operated plate inside the carburetor that opens to admit air into the secondary venturi at higher throttle openings. This valve is part of the carb body and is usually located on the side of the carb opposite the throttle linkage.
- Typically a circular or rectangular valve plate inside the carb housing, sliding or pivoting to expose the secondary air passages.
- In many two-barrel or four-barrel carbs, you access it by removing the air cleaner and possibly the top cover of the carb.
- Activation is via a linkage or vacuum diaphragm connected to the intake manifold, opening as RPM rises or throttle is opened.
For carburetors, consult the specific model manual to locate and service the secondary air valve, since designs vary widely by brand and era.
Summary
The exact position of the secondary air valve varies by system and vehicle. In most modern cars with secondary air injection, look near the exhaust manifold, air pump, or intake/throttle area for a small solenoid or vacuum valve. In older carbureted engines, the secondary air valve is inside the carburetor body, near the secondary venturi. Always refer to your vehicle’s service documentation to confirm the precise location and to obtain correct service procedures.
What are the symptoms of a bad secondary air injection valve?
Potential complaints:
- Secondary air pump does not start after a cold start.
- The engine compartment smells charred.
- Melting traces on the electrical contacts of the secondary air pump.
- P0410 “Malfunction”
How to check secondary air valve?
The secondary air valve can be quickly inspected in an easy way:
- Loosen the connecting hose on the secondary air non-return valve leading to the secondary air pump.
- If there are deposits on this side of the valve (finger test, see Fig.
- Inspect the secondary air pump and replace it if necessary.
What is a secondary air valve?
Secondary-air system components
The secondary-air pump draws in ambient air and injects it into the exhaust manifold downstream of the exhaust valves. There is a separate integrated air filter if the air is not drawn in from the intake system but rather directly from the engine compartment.
Where is the secondary air system located?
The secondary air injection pump is usually placed near the engine. However, it may sometimes be hidden in the engine bay.
