4 Symptoms of a Bad Secondary Air Injection Pump
Advanced exhaust components reduce a vehicle’s environmental impact and meet strict regulations. A lesser known device is the secondary air injection pump, which delivers additional airflow after starting to further neutralize exhaust fumes. But these pumps inevitably fail as they age.
A range of symptoms, from mild to severe, indicate a problem. We’ll look at what signs to look out for if this emissions helper itself needs help, as well as the costs associated with replacing a secondary air injection pump.
What is a Secondary Air Injection Pump?
Modern vehicles are equipped with a special secondary air injection pump that directs air into the vehicle’s exhaust stream. This is done to compensate for the natural rich condition that occurs during engine start-up. This pump runs for approximately 30-120 seconds after start-up and operates in response to a power request from the vehicle’s ECM/PCM.
This additional air flow is used to further neutralize the vehicle’s harmful emissions, especially when combined with very rich driving conditions. The presence of this fresh air helps convert carbon monoxide to carbon dioxide and hydrocarbons to condensation. This significantly reduces the vehicle’s carbon dioxide emissions.
The operation of the secondary air pump is monitored by the vehicle’s O2 sensors. The secondary air injection pump circuit also includes an air solenoid, a relay, a check valve, and various vacuum lines. Failure of any of these critical components can cause total or partial system failure.
Other Components of the Secondary Air Injection System
While the pump is essential, there are other parts that make up the secondary air injection system to reduce vehicle emissions.
1. The control relay is responsible for controlling the electric pump. This relay works with the engine control unit to ensure the pump is operating efficiently and delivering the required amount of air.
2. The air pressure control valve controls the flow of air through the system. It helps complete the secondary combustion process by regulating the air supply to the exhaust manifold.
3. The combination valve works in conjunction with the air pressure control valve. Its main role is to prevent exhaust gases from entering the air pump. This protective measure keeps the system functioning and prevents damage to the pump.
4. The Engine Control Unit (ECU) acts as the brains and central point that coordinates all these components (and most other systems in the vehicle). Determine when to run the air pump and adjust the necessary parameters to ensure the secondary air injection system operates efficiently.
Secondary Air Injection Pump Location
Below are the most common symptoms associated with a faulty secondary air injection pump.
1) Check Engine Light
One of the most obvious symptoms of a faulty secondary air injection pump is the sudden illumination of your vehicle’s Check Engine Light. This occurs when your vehicle’s ECM/PCM does not register a lean condition when the secondary air injection pump is turned on. The typical result is the storage of active diagnostic trouble codes such as P0410, P0411, P0412, P2440, or P2442.
2) Idling Irregularities
In many cases, a poorly functioning secondary air injection pump will cause your vehicle’s engine to idle erratically. In some cases, the vehicle’s idle speed may drop to low speeds, resulting in the engine sputtering or stalling out completely. This is due to the obvious effect that secondary air injection, or lack thereof, has on the O2 sensor feedback.
3) Decreased Performance
Secondary air injection pump failure can also affect the overall performance of the vehicle. In most cases, this loss of power is noticed as a noticeable lack of power when accelerating. The severity of this symptom may or may not worsen over time.
4) Failing Emissions Tests
Failure of a vehicle’s secondary air injection pump may also become evident during legally required emissions testing. This is because if the secondary air injection circuit does not function properly, the vehicle’s exhaust will tend to run very rich on start-up.