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P0418MinorEmissions

P0418: How to Diagnose & Fix — Secondary Air Injection System Relay A Circuit

9 vehicles · 3 makes · $100-$4,000 repair

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How to diagnose and fix P0418: most-reported vehicles

Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.

Toyota Tundra · 2005–2013

Community reported
8,500 owners
Link to this issueError Codes:P0410P0411P0412P0418P2440P2443P2445P2447P0419

The secondary air injection pump is prone to failure due to water intrusion. The electric motor is located in the wheel well with moisture exposure, and the rubber boot covering the motor traps water, causing the pump to short circuit. This triggers check engine lights with codes P2440, P2443, P2445, P2447, P0418, or P0419. Some vehicles may enter limp mode.

Common Symptoms

  • Check engine light illumination
  • Jet engine noise on cold startup
  • Decreased fuel economy
  • Limp mode activation
  • Rough idle when cold

How to Fix

Toyota issued a service bulletin for 2007-2010 models covering replacement of the entire air injection system. Repair costs range from $2,000-$4,000 for OEM replacement. Some owners opt for aftermarket bypass kits with block-off plates.

What you need to fix it

Only diagnosis- and fitment-reviewed repair parts are linked here.

  • Toyota 17610-0S010 genuine secondary-air pump assembly

    replace the corresponding pump only when active testing and the applicable Toyota program identify it as failed Fitment/availability: Cataloged for selected 2007-2013 Tundra applications; exact engine, side/quantity, DTC branch, VIN and …

    ToyotaPartsNow
  • Toyota 17610-0S030 genuine secondary-air pump assembly

    replace the program-matched pump after active-test confirmation, with all required valves, inlets, gaskets and calibration handled separately Fitment/availability: Cataloged for selected 2012-2021 4.6L/5.7L applications; on this card use…

    ToyotaPartsNow

As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.

Owner tips & cautions

  • TipDIY repairs can save significantly - dealer charges $2,000-$4,000 but DIY costs are typically 50-70% less
  • TipConsider OEM parts for critical components like sensors and electrical parts - aftermarket can be unreliable
  • TipGet a proper diagnosis before replacing parts - similar symptoms can have different causes
Typical repair cost:$1,500 - $4,000

Research This Issue

Based on 8,500 owner reports

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Community Reported
High Confidence8,500 owner reportsLast reported by owners Feb 2024Reviewed Feb 2026

Toyota Sequoia · 2001–2009

Community reported
2,400 owners
Link to this issueError Codes:P0410P0411P0412P0418P2440P2442

The 4.7L 2UZ-FE's secondary air injection system fails due to corroded air switching valves (ASVs) and seized air pumps. Moisture enters the system and corrodes internal components. Causes check engine light with P2440/P2442 codes.

Common Symptoms

  • Check engine light with P2440 or P2442 codes
  • Rough idle on cold start
  • Ticking or buzzing noise from air pump on startup
  • Failed emissions testing

How to Fix

Replace air switching valves (Toyota 25701-50040 and 25702-50011) and air injection pump (Toyota 17610-0S010) if seized. Many owners bypass the system entirely with block-off plates since it only operates during cold start for emissions. Bypass plates available from Trail Gear or fabricated from aluminum.

What you need to fix it

Only diagnosis- and fitment-reviewed repair parts are linked here.

  • Toyota 17600-0F010 secondary air injection pump assembly

    replace a debris-damaged secondary-air pump after bulletin diagnosis Fitment/availability: Exact pump listed by T-SB-0230-12 Rev1 for an eligible 2005-2007 Sequoia 2UZ-FE; replace only when bulletin inspection finds debris in the pump Fi…

    ToyotaPartsDeal
  • Toyota 25710-50022 air switching valve assembly

    replace the corresponding failed or debris-damaged air switching valve Fitment/availability: Exact air switching valve assembly listed by T-SB-0230-12 Rev1; use only on the diagnosed valve branch and confirm VIN before ordering Fitment/a…

    AutoPartsPrime
  • Toyota 25720-50011 electric air control valve No. 1

    1 valve only when its bulletin diagnostic branch confirms failure or damage Fitment/availability: Exact No. 1 valve listed by T-SB-0230-12 Rev1; not interchangeable with the No.

    ToyotaPartsDeal
  • Toyota 25720-50020 electric air control valve No. 2

    2 valve only when its bulletin diagnostic branch confirms failure or damage Fitment/availability: Exact No. 2 valve listed by T-SB-0230-12 Rev1; not interchangeable with the No.

    ToyotaPartsDeal
  • Toyota 89580-34012 air injection control driver

    replace the air-injection control driver on the bulletin's residual-code branch Fitment/availability: Exact driver identified by T-SB-0230-12 Rev1; use only if P0418 or P2445 remains after the applicable mechanical repair and confirmatio…

    ToyotaPartsDeal
  • Toyota 17171-50030 intake manifold-to-head gasket No. 1

    reseal both intake-manifold-to-head joints during the applicable repair Fitment/availability: Exact gasket listed by T-SB-0230-12 Rev1; bulletin quantity is two when the applicable air-injection repair requires intake-manifold removal Fi…

    ToyotaPartsDeal
  • Toyota 17377-50010 air tube gasket No. 4

    replace disturbed air-tube seals during the bulletin repair Fitment/availability: Exact air-tube gasket listed by T-SB-0230-12 Rev1; bulletin quantity is four for the applicable repair Fitment/availability: Ships in 1-3 business days wit…

    ToyotaPartsDeal

As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.

Typical repair cost:$100 - $2,000

Research This Issue

Based on 2,400 owner reports

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Community Reported
High Confidence2,400 owner reportsLast reported by owners Feb 2026Reviewed Feb 2026

Toyota Sequoia · 2008–2019

Community reported
1,100 owners
Link to this issueError Codes:P0410P0411P0412P0418P2440P2441P2442P2443P2444P2445

2nd-gen Sequoias with the 5.7L 3UR-FE also suffer from secondary air injection pump failures, similar to the 1st gen but with updated part numbers. The pump seizes from internal moisture corrosion, triggering P2440-P2445 codes and check engine light.

Common Symptoms

  • Check engine light with P2440-P2445 codes
  • Loud buzzing or grinding on cold start
  • Air pump not engaging on startup
  • Failed emissions test

How to Fix

Replace secondary air injection pump (Toyota 17610-0S010 or Dorman 306-058). Replace air switching valves if corroded. Aftermarket pumps are available at lower cost. Some owners install check valves in the air line to prevent moisture backflow into the pump.

Typical repair cost:$300 - $1,500

Research This Issue

Based on 1,100 owner reports

GoogleRedditYouTubeNHTSA
Community Reported
High Confidence1,100 owner reportsLast reported by owners Feb 2026Reviewed Feb 2026

Toyota Tacoma · 2005–2011

Link to this issueError Codes:P0412P0418P2440P2441P2442P2443P2445P2447

Tacomas with the 1GR-FE 4.0L V6 are known for failures of the secondary air injection system, including the air pump and switching valves. Moisture intrusion and valve sticking can trigger check-engine lights and force the truck into reduced-power or limp mode. Owners frequently report sudden loss of acceleration along with expensive dealer repair estimates because the intake manifold often must be removed to access components.

Common Symptoms

  • check engine light
  • TRAC/VSC lights on
  • reduced power or limp mode
  • poor acceleration
  • cold-start abnormal pump noise

How to Fix

Diagnose with a scan tool and active tests to determine whether the pump, bank valves, or control circuits have failed. Repair usually involves replacing the failed air pump and/or switching valves, checking related vacuum/electrical connections, and clearing codes after verification. Some owners install bypass modules, but emissions-compliant repair with quality parts is the proper fix.

What you need to diagnose it

The repair instructions explicitly call for reading stored codes. Use a scanner that can read the named code families before choosing a repair.The recommended scanner supports these code families; confirm your exact year, model and module coverage before buying.

  • ANCEL AD310 Classic OBD-II Scanner

    Read & clear engine (P) codes

    $20–$40View

As an Amazon Associate, we earn from qualifying purchases. Prices are approximate and may vary.

Reading and clearing the code is DIY work. Module replacement or reprogramming is not — most modules are VIN-programmed, so a new one does nothing until a shop codes it to your car. Check for an open recall or service bulletin before buying anything.

What you need to fix it

Only diagnosis- and fitment-reviewed repair parts are linked here.

  • Toyota 17610-0W020 genuine secondary-air pump assembly

    replace the pump only when Toyota's active-test and DTC/inspection branch requires pump replacement Fitment/availability: Toyota's T-SB-0333-17 repair part for the VIN-specific 2012 Tacoma 4.0L 1GR-FE Mexico-production branch; confirm VI…

    ToyotaPartsDeal
  • Toyota 25710-31022 genuine secondary-air switching-valve assembly

    replace a moisture-damaged or stuck switching-valve assembly as part of the Toyota-prescribed repair set Fitment/availability: Superseding switching-valve assembly specified by T-SB-0333-17 for the affected 2012 Tacoma 1GR-FE Mexico-prod…

    ToyotaPartsDeal
  • Toyota 17613-0P010 genuine air-pump protective cover

    reduce repeat filter damage after the confirmed secondary-air-system repair Fitment/availability: Toyota T-SB-0333-17 and CSP ZHA cover for the affected 2012 Tacoma 1GR-FE repair; confirm VIN and use with the complete prescribed pump/val…

    ToyotaPartsDeal

As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.

Owner tips & cautions

  • TipIf the truck enters limp mode with P2440-series codes, diagnose the air injection system before replacing unrelated sensors.
  • TipAddress water intrusion and inspect hoses/connectors during repair, since moisture is a common contributor to repeat failures.
Typical repair cost:$1,200 - $3,000
Sources for this issue (2)
  • Toyota Warranty Enhancement Program ZE3 for Secondary Air Injection Systemtsb
  • TacomaWorld secondary air injection pump/valve failure threadforum

Research This Issue

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Community Reported
High Confidence

Subaru Forester · 2009–2013

Link to this issueError Codes:P0410P0418P2444P2445

On turbocharged Forester XT models, the relay controlling the secondary air injection (SAI) pump can fail in the closed position, leaving the air pump running continuously. Sustained operation overheats the pump, which can melt surrounding components and create a fire risk even with the vehicle parked. Subaru recalled about 100,000 turbo vehicles (Forester XT, Impreza WRX/STI, Legacy/Outback turbo) for the defect.

Common Symptoms

  • Burning / melting smell from engine bay
  • Air pump audibly running after engine warmed up or off
  • Check engine light with SAI codes
  • Blown SAI-circuit fuse

How to Fix

Free recall repair under Subaru campaign WTM-73 (NHTSA 16V-738): the dealer replaces the secondary air injection pump relay. If the pump itself was already damaged by prolonged overheating it is replaced as well. Owners of turbo XT models should confirm the recall has been completed by VIN, as completion rates on older vehicles are often incomplete.

Find a Subaru dealer

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Call to confirm they service Subaru vehicles and check your VIN, recall eligibility, parts availability, and appointment options.

Typical repair cost:$0 - $120
Sources for this issue (3)
  • Subaru Recall WTM-73: Power Relay May Fail Allowing Air Pump to Overheat (NHTSA 16V738000)recall
  • Subaru Recall: Air Injection Pump Overheats (16V738000)recall
  • Subaru WRX/STI, Forester XT, Outback Recall for Fire Risk Reaches US Modelsarticle

Research This Issue

GoogleRedditYouTubeNHTSA
Community Reported
High ConfidenceVerifiedReviewed Jun 2026

Find P0418 by make

Browse every documented model and issue for your make.

Lexus · 1 issueSubaru · 2 issuesToyota · 7 issues

P0418 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 P0418 mean?

P0418 stands for "Secondary Air Injection System Relay A Circuit." This code means the Engine Control Module detected a fault in the control circuit for Secondary Air Injection (AIR) System Relay 'A'. The secondary air injection system pumps fresh air into the exhaust during cold starts to help the catalytic converter heat up faster and burn off pollutants, and Relay A switches power to that air pump. P0418 sets when the computer commands the relay but sees an abnormal voltage or no response on its control circuit. This is an emissions-related fault that may keep the air pump from running when needed.

What are the most common causes of P0418?

The most common causes of P0418 are: Faulty secondary air injection relay (Relay A), Open, shorted, or corroded relay control wiring, Poor power or ground feed to the relay, Failed secondary air injection pump (drawing wrong current), Corroded relay socket or connector, Blown fuse in the air injection circuit, Faulty ECM relay driver. The specific cause varies by vehicle.

How much does it cost to fix P0418?

Repair costs for P0418 range from $100 to $4,000, depending on the vehicle and root cause.

Which vehicles are affected by P0418?

Au7o has documented P0418 across 9 vehicle models from 3 manufacturers: Lexus, Subaru, Toyota.

Related codes

  • P0410 · Secondary Air Injection System Malfunction
  • P0411 · Secondary Air Injection System Incorrect Flow Detected
  • P0412 · Secondary Air Injection System Switching Valve A Circuit
  • P0413 · Secondary Air Injection System Switching Valve "A" Circuit Open
  • 01447 · EVAP System (VAG)
  • P0030 · HO2S Heater Control Circuit (Bank 1 Sensor 1)
  • P0031 · HO2S Heater Control Circuit Low (Bank 1 Sensor 1)
  • P0037 · HO2S Heater Control Circuit Low (Bank 1 Sensor 2)
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.

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