Parts Department

Subaru Secondary Air Injection System

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Images may differ depending on model Genuine Subaru Secondary Air Valves Genuine Subaru Secondary Air Pumps Ring for Prices Valves From £198 to £250 Pumps From £365 to £655 The price will depend on the model All prices Exclude VAT @ 20%  Delivery extra. Fitting Service Available.

Subaru Secondary Air Pump & Secondary Air Valves

With a fault on the Secondary Air Injection System the following OBDII codes are possible depending on the make and model:

P1410 Secondary Air Injection System Switching Valve Stuck Open
P1444 Secondary Air Injection System Switching Valve Stuck Open
P1418 Secondary Air Injection System Control "A" Circuit Shorted
P2430 Secondary Air Injection System Air Flow/Press Sensor Circ Bank1
P2431 Secondary Air Injection System Air Flow/Press Sensor Circ Range/Perf Bank1
P2432 Secondary Air Injection System Air Flow/Press Sensor Circ Low Bank1
P2433 Secondary Air Injection System Air Flow/Press Sensor Circ High Bank1
P2434 Secondary Air Injection System Air Flow/Press Sensor Circ Interm/Erratic Bank1
P2435 Secondary Air Injection System Air Flow/Press Sensor Circ Bank2
P2436 Secondary Air Injection System Air Flow/Press Sensor Circ Range/Perf Bank2
P2437 Secondary Air Injection System Air Flow/Press Sensor Circ Low Bank2
P2438 Secondary Air Injection System Air Flow/Press Sensor Circ High Bank2
P2439 Secondary Air Injection System Air Flow/Press Sensor Circ Interm/Eratic Bank2
P2440 Secondary Air Injection System Switching Valve Stuck Open Bank1
P2441 Secondary Air Injection System Switching Valve Stuck Closed Bank1
P2442 Secondary Air Injection System Switching Valve Stuck Open Bank2
P2443 Secondary Air Injection System Switching Valve Stuck Closed Bank2
P2444 Secondary Air Injection System Pump Stuck On Bank1
P2445 Secondary Air Injection System Pump Stuck Off Bank1
P2446 Secondary Air Injection System Pump Stuck On Bank2
P2447 Secondary Air Injection System Pump Stuck Off Bank2

Possible Causes:

Short in Air Pump circuit
Blown Fuse
Fault in Air pump assembly
Faulty Pressure Sensor
Pressure Sensor harness is open or shorted
Pressure Sensor circuit poor electrical connection
Secondary Air Valve Stuck Open
Secondary Air Valve Stuck Closed
Air Switching Valve harness is open or shorted
Air Switching Valve circuit poor electrical connection

How it works

When the engine is cold, on start up and for up to 60 seconds air is injected into the exhaust to clean up the extra-rich exhaust and raises the temperature of the exhaust to bring the catalytic converter to operating temperature quickly. To accelerate the activation of catalyst when warming up the engine, the secondary air injection system pumps the air to the exhaust system by an air pressure pump. The secondary air is supplied by the air pump and it is pumped to the exhaust through the air switching valves (AKA Secondary Air Injection Valves). Open and close movement of the air switching valve is regulated by the Vacuum Switching Valve (VSV).The air pump and the air switching valve are observed by the Engine Control Module (ECM AKA Engine Management System AKA Engine Control Unit AKA ECU) and are used to detect malfunction in this system. The ECM monitors the secondary air injection system and detects the malfunction using a pressure sensor located on the air switching valve.

The ECM observes the pressure in the secondary air passage using the pressure sensor located on the air switching valve in the secondary air injection system. The sensor detects an exhaust pressure in the secondary air passage.

If the pressure level from the sensor in the Secondary Air Valve (air switching valve) has not reached a certain level despite the ECM turning on the air pump, or if the pressure level exceeds the threshold despite the ECM turning off the air pump, the ECM interprets this as a fault in the secondary air injection system and the code is set.

Common Problem
One of the more common problems with this type of secondary air injection system (and it is not restricted to Subaru cars, many other makes of car also have similar secondary air sytems fitted) is that the secondary air pump is pumping (often damp) air from the atmosphere directly through the secondary air valves and into the exhaust when the engine is cold. This damp air can condense moisure (water) inside the secondary air valves. The air valves close after approximately 40 seconds and the moisture is trapped before the secondary air valves can get hot enough to evaporate the moisture. This can cause corrosion inside the valves leading to the valves(s) sticking open or closed.