Estimates last updated October 16, 2025

2021 Toyota 4Runner Air Injection System Check Valve Replacement Cost

The average cost for a 2021 Toyota 4Runner Air Injection System Check Valve Replacement is between $466 and $500.

Labor costs are estimated between $73 and $107 while parts are typically priced around $393.
This range does not include taxes and fees, and does not factor in your unique location. Related repairs may also be needed.

Air Injection System Check Valve Replacement

What is an air pump check valve?

The air pump check valve is a one way valve that allows air from the air pump to enter the exhaust system. More importantly, it prevents hot exhaust gases from entering the Secondary Air Injection System.

Air Injection System Check Valve Replacement

How does the air pump check valve work?

The check valve can be vacuum operated or strictly mechanical in nature. A mechanical valve will simply let pressurized airflow in only one direction. A vacuum operated check valve will use a controlled vacuum source to open and close the valve at the appropriate time.

What are the symptoms related to a bad air pump check valve?

When the air pump check valve is malfunctioning, the vehicle may perform normally, but may fail an emissions inspection and get poor gas mileage. The Check Engine Light may illuminate with a code set for the secondary air injection system. A melted Secondary Air Injection rubber hose could be caused by a leaking check valve.

Can I drive with an air pump check valve problem?

A vehicle should not be driven if the check valve is allowing hot exhaust gasses into the rubber hoses of the Secondary Air Injection system as this could result in damage to the hoses and other components. If the valve is simply restricted and not allowing flow in either direction, it should be OK to temporarily drive the vehicle. Get this fixed by a RepairPal Certified Shop

How often do air pump check valves need to be replaced?

Toyota Air Injection System Check Valve Replacement Cost Estimates

The average cost for a Air Injection System Check Valve Replacement is between $466 and $500 but can vary from car to car.

Toyota 4Runner Air Injection System Check Valve Replacement Cost by Year

The average cost for a Toyota 4Runner Air Injection System Check Valve Replacement is between $466 and $500 but can vary from car to car.

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Air Injection System Check Valve Replacement

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What is an air pump check valve?

How does the air pump check valve work?

What are the symptoms related to a bad air pump check valve?

Can I drive with an air pump check valve problem?

How often do air pump check valves need to be replaced?

Whether or not a Secondary Air System Check Valve(s) will fail can vary greatly for different makes and models. Geographic locations where road salt is used may see more failures because rust can greatly shorten the life the check valve(s).

How are air pump check valve issues diagnosed?

Most commonly an illuminated check engine light would lead to retrieval of a fault code indicating a problem with a Secondary Air System check valve. A suspect valve would then be tested for proper operation, unrestricted flow in one direction and no flow in the other. Heat damaged Secondary Air Injection hoses and/or components would also lead to inspection of the check valve(s) for proper operation.

How is an air pump check valve replaced?

A Secondary Air System Check Valve will either screw directly onto a pipe connected to the exhaust system or bolt onto a metal flange that is part of the exhaust system. On some models, various components my need to be removed to gain access to the valve. A bit of penetrating oil on the mounting threads or bolts can greatly aid in removal of the old valve.

RepairPal Recommendations for air pump check valve issues

Care should be taken when working around hot exhaust system components. Threads should be treated with a penetrating oil prior to removing an AIR System Check Valve. It may be a bit easier to remove a check valve when the engine and components are warm as opposed to stone cold. Always try and confirm you have the correct part prior to removing the old one. Additional parts of the Secondary Air System can be damaged if the engine is run with a failed check valve that is allowing hot exhaust gases to pass through it.

What to look out for when dealing with air pump check valve issues

Rust can develop on exhaust system components making disassembly difficult. Penetrating oil should be used on threads prior to removal of any components. Care should be taken when working around a hot exhaust system.

Can I replace the air pump check valve myself?

Repairing your own car is an extremely rewarding process that can also save you money. But before you dive in, it’s important to be sure the issue has been properly diagnosed. Seemingly obvious symptoms can lead the inexperienced down a rabbit hole of replacing parts that don’t fix the problem. Proper diagnosis can save more money than guessing at what’s broken! If you're unsure you have the right tools or experience to diagnose a problem, consider reaching out to a RepairPal Certified Shop. Care should be taken when working around a hot exhaust system. Take note of any components that would need to be removed to replace the check valve. Make sure you have the tools and knowledge to remove and properly replace all that is required.