P2440 on Lexus: How to Diagnose & Fix
Secondary Air Injection System Switching Valve Stuck Open (Bank 1)
1 Lexus model · 2 documented issues · $800-$3,500 repair
P2440 on Lexus by model: symptoms, diagnosis and fix
The secondary air injection (SAI) system pump and switching valves fail due to moisture intrusion and corrosion. The SAI pump introduces fresh air into the exhaust during cold starts to reduce emissions, but the pump motor corrodes internally and the switching valves stick. This triggers a check engine light with SAI-related codes.
Common Symptoms
- Check engine light with P2440/P2441/P2442 codes
- Rough idle on cold start
- Failed emissions inspection
- Whirring noise from passenger side of engine on cold start
How to Fix
Replace the secondary air injection pump and switching valves. Clean or replace the air injection check valves. Clear codes and verify operation. Some owners in non-emissions-testing states choose to bypass the system entirely with a tune.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- 17600-0F010 genuine Lexus secondary-air injection pumpOEM17600-0F010
Replace a commanded-test-confirmed failed secondary-air pump Fitment/availability: Live page explicitly fits 2004-2009 GX470 2UZ-FE/UZJ120. It does not verify the issue's 2003 year.
- 25710-50022 genuine Lexus secondary-air switching/diverter valveOEM25710-50022
Replace the diagnosed failed main air-switching/diverter valve Fitment/availability: Live page explicitly fits 2004-2009 GX470 2UZ-FE and supersedes 25710-50020/21.
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Owner tips & cautions
- TipReplace both the pump AND the switching valves at the same time — if one has failed, the other is likely close behind. The valves are $150 each but save a second repair.
The secondary air injection system pumps air into the exhaust on cold start to light the catalysts faster. On the GX 460 it fails in two related ways. The foam filter inside the air injection pump disintegrates with age and the debris is drawn into the system, blocking the air switching valves and lines downstream. Separately, and in the large majority of failures, the diverter or air switching valve corrodes from moisture contamination. Either failure sets emissions codes and drops the vehicle into limp mode, which owners experience as a sudden dramatic loss of power on a cold morning, usually on the first drive of the day. Lexus acknowledged the defect for 2010-2013 GX 460 vehicles with the 1UR-FE engine in a Special Service Campaign (bulletin L-SB-0028-14) covering MIL-on conditions with DTC P0418, P2440, P2442 and/or P2445, under which the pump filter and air switching valves are replaced at no charge. This is the same architecture that troubles the 2010-2013 Tundra, Sequoia, and LX 570.
Common Symptoms
- Sudden loss of power and limp mode on cold start
- Check engine light with secondary air injection codes
- Loud whirring or buzzing from the engine bay on cold start
- Rough running for the first minute after a cold start
- Failed emissions test
How to Fix
Before paying for anything, check the VIN against the Lexus Special Service Campaign (bulletin L-SB-0028-14): for affected 2010-2013 GX 460 vehicles the dealer replaces the air injection pump filter with an improved-design part and replaces the air switching valves free of charge, and will replace the air injection pump itself as needed at no cost. Many owners pay several thousand dollars for this repair without ever learning the campaign exists, so make this call first. If the vehicle is outside the campaign, diagnose which half has failed before buying parts, because the pump and the valves are priced very differently. Pull the codes and inspect the pump's foam filter — if it has disintegrated, replacing valves alone guarantees a repeat failure because the debris is still in the system, so the lines must be cleared too. If the pump filter is intact, the odds strongly favor a corroded diverter or air switching valve. Fit the improved-design filter so the failure does not recur. Some owners fit an aftermarket bypass or delete to escape the failure loop, but understand that this defeats an emissions control device, will fail inspection in most states, and is illegal to perform on a road vehicle.
Sources for this issue (4)
- Lexus Special Service Campaign L-SB-0028-14 — Secondary Air Injection System (2010-2013 GX 460)tsb
- GX460 check engine light, P2440, P2442, P2445 and/or P0418 — CarSpecarticle
- 11 Most Common Lexus GX 460 Problems (Explained) — Engine Patrolarticle
- 2010-2013 GX 460 Special Service Campaign — IH8MUD Forumforum
P2440 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P2440 mean on a Lexus?
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 Lexus it is documented across 1 model: GX.
What are the most common causes of P2440?
The most common causes of P2440 are: 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. The specific cause varies by vehicle.
How much does it cost to fix P2440 on a Lexus?
Published repair estimates on Lexus range from $800 to $3,500 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P2440 on a different make?
View P2440 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.