P2440 on Subaru
Secondary Air Injection System Switching Valve Stuck Open (Bank 1)
P2440 on Subaru vehicles indicates secondary air injection system switching valve stuck open (bank 1). Au7o has documented this code across 2 Subaru models — most commonly on WRX, WRX STI. P2440 indicates the secondary air injection (SAI) system's switching/diverter valve on engine bank 1 is stuck open. The secondary air system briefly pumps fresh air into the exhaust at cold start so the catalytic converter heats up and lights off faster, cutting cold-start emissions. The computer commands this valve closed once warm-up is done; if it senses the valve hasn't closed (air is still flowing when it shouldn't be), it sets this code. A stuck-open valve can let exhaust pressure or moisture back into the air pump and skews the oxygen sensor readings during warm-up. Typical repair costs on Subaru range from $600 to $2,200, depending on the specific model and root cause.
Common Causes of P2440
- •Air switching/diverter valve stuck open or seized
- •Carbon, rust, or debris fouling the valve
- •Faulty valve vacuum control solenoid or leaking vacuum line
- •Corroded or moisture-damaged secondary air pump
- •Wiring or connector faults at the valve solenoid
- •Clogged or failed combination/check valve
- •Vacuum leak preventing the valve from closing
P2440 on Subaru by Model
Subaru WRX(1 issue)
- Secondary Air Injection Pump and Switching Valve Failure Triggering CEL and Limp Mode2006-2014
Turbo EJ255/EJ257 WRX models equipped with the secondary air injection system commonly develop failures of the air pump, pressure sensor, or the air switching valves. Moisture intrusion and corrosion can cause the valves to stick or the pump to seize, which sets emissions faults and on many cars can reduce power or force a limp-home condition. Owners typically report a check-engine light shortly after cold start, often with rough cold operation or an audible pump noise before failure.
Subaru WRX STI(1 issue)
- Air Injection System (Secondary Air Pump/Valves) Failure (P0410/P244x)2008-2014
Subaru WRX STI models equipped with the EJ257 and secondary air injection commonly develop failures of the air pump and/or the air switching valves, often due to moisture intrusion and internal corrosion that causes the valves to stick. Owners typically see a check engine light with cold-start drivability changes and may fail emissions/inspection due to stored air injection codes. This issue is widely documented in owner reports and Subaru service information/TSBs covering secondary air injection diagnostics and component replacement.
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What does P2440 mean on Subaru?▼
P2440 stands for "Secondary Air Injection System Switching Valve Stuck Open (Bank 1)." P2440 indicates the secondary air injection (SAI) system's switching/diverter valve on engine bank 1 is stuck open. The secondary air system briefly pumps fresh air into the exhaust at cold start so the catalytic converter heats up and lights off faster, cutting cold-start emissions. The computer commands this valve closed once warm-up is done; if it senses the valve hasn't closed (air is still flowing when it shouldn't be), it sets this code. A stuck-open valve can let exhaust pressure or moisture back into the air pump and skews the oxygen sensor readings during warm-up. On Subaru specifically, this code is documented across 2 models.
What causes P2440 on Subaru vehicles?▼
Common causes on Subaru: Air switching/diverter valve stuck open or seized, Carbon, rust, or debris fouling the valve, Faulty valve vacuum control solenoid or leaking vacuum line, Corroded or moisture-damaged secondary air pump, Wiring or connector faults at the valve solenoid. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P2440 on a Subaru?▼
Repair costs on Subaru range from $600 to $2,200, depending on the specific model and root cause.
Which Subaru models have P2440 documented?▼
Au7o has documented P2440 on 2 Subaru models: WRX, WRX STI.