3rd Gen Tacoma Secondary Air Injection Bypass: Complete Guide for 2016-2023 Toyota Tacoma Owners

Understanding the Secondary Air Injection System (SAI) in 3rd Gen Tacoma

The 3rd generation Toyota Tacoma (2016-2023) with the 2GR-FKS 3.5L V6 engine comes factory-equipped with a Secondary Air Injection System. This emissions control device injects fresh air into the exhaust ports during cold starts to help the catalytic converters reach operating temperature faster, significantly reducing hydrocarbon (HC) and carbon monoxide (CO) emissions in the first 60-90 seconds after startup.

The system consists of:

• Two electric air pumps (one per cylinder bank)

• Two air switching valves (ASV)

• Air injection manifolds drilled into the cylinder heads

• Vacuum solenoids, pressure sensors, reed valves, and a complex network of steel and rubber hoses

• Dedicated SAI fuse and relay in the engine bay fuse box

While effective for emissions compliance, the system is notoriously fragile on the 3rd gen Tacoma, especially in regions with high humidity, road salt, or off-road use.

Most Common Secondary Air Injection Failure Symptoms

Owners typically notice these warning signs:

• Loud whining or grinding noise from the air pumps on cold start (often described as a dying vacuum cleaner)

• Check Engine Light with codes P0418, P0419, P2440, P2441, P2442, P2443, P2445, P2447

• Reduced power or limp mode in extreme cases

• Water intrusion damage visible on air pump housings (corrosion, rust, seized motor)

• Failed pressure sensor readings despite functional pumps

• Blown SAI fuse (30A) due to seized pump drawing excessive current

Toyota issued a Technical Service Bulletin (T-SB-0144-17) acknowledging premature failure, but the warranty enhancement only extends coverage to 10 years/150,000 miles under specific conditions.

Why Owners Choose Secondary Air Injection Bypass

Many 3rd gen Tacoma owners living outside of strict emissions testing states (or those who off-road extensively) opt for a permanent bypass solution because:

• Genuine Toyota replacement air pumps cost $800–$1,200 each (two required)

• Complete OEM system replacement often exceeds $3,500–$4,500 at dealership

• Labor is extremely intensive – cylinder head removal sometimes needed to replace rusted air injection manifolds

• Failures frequently reoccur even after expensive repair due to inherent design flaw (poor water drainage and unsealed pumps)

• Bypass eliminates cold-start noise and future repair costs permanently

Popular Bypass Methods Compared

1. Resistor + Block-Off Plate Kit (Most Common)

The simplest and most widely used method involves:

• Installing 2.2–2.7 ohm 50W resistors (one per pump circuit) to fool the ECU into thinking pumps are operating normally

• Aluminum or stainless block-off plates with gaskets bolted over the cylinder head air injection ports

• Optional silicone caps over vacuum lines and pressure sensor ports

Pros: Completely reversible, cheapest option (~$80–$150), no welding required

Cons: Some owners report occasional P2445 code return in very cold weather

2. Hewitt Technologies SAIS Bypass Module

A plug-and-play electronic emulator that connects directly to the factory wiring harness.

• Actively simulates correct pressure sensor and pump current draw

• Weatherproof housing, lifetime warranty from Hewitt

• No block-off plates required (pumps can stay in place but unplugged)

Pros: Cleanest installation, most reliable long-term, zero codes reported by thousands of users

Cons: Higher cost (~$329–$369)

3. Custom ECU Tune / Flash Delete

Professional tuners (KDMax, OV Tune, VF Tuner) offer permanent SAI deletion through custom calibration.

• Completely removes SAI monitoring from ECU logic

• Often combined with performance improvements

Pros: Most comprehensive solution, slight power/fuel economy gain from leaner cold-start calibration

Cons: Requires professional flashing tool, may affect warranty, not legal in emissions-testing states

4. Manual Relay Bypass (Old-School Method)

Involves wiring a relay that only activates pumps when the ECU commands, but resistors still used.

Rarely recommended anymore due to complexity.

Step-by-Step Installation Guide for Resistor + Block-Off Plate Bypass

Tools needed: 10mm, 12mm, 14mm sockets, torque wrench, gasket scraper, anti-seize, RTV silicone

1. Disconnect battery negative terminal

2. Remove engine cover and intake tubing for access

3. Unplug both air pump connectors (driver and passenger side near frame rails)

4. Solder or crimp 2.2–2.7 ohm 50W aluminum resistors into the pump harness (pins 1 and 4 typically)

5. Mount resistors to metal surface with heatsink compound or zip-tie away from heat

6. Remove air injection manifold covers on both cylinder heads (four 12mm bolts each side)

7. Thoroughly clean gasket surfaces

8. Install CNC-machined block-off plates with new gaskets (torque to 15 ft-lbs in cross pattern)

9. Cap vacuum lines to air switching valves with 5/16" vacuum caps and zip ties

10. Plug pressure sensor connectors with dummy plugs or wrap in electrical tape

11. Clear all codes with OBD2 scanner

12. Reconnect battery and verify no CEL

Total time: 2–4 hours for experienced DIY.

Best Aftermarket Bypass Kits in 2025

• Hewitt Technologies Gen3 Tacoma SAIS Bypass Module – gold standard for zero codes

• Dobinsons Direct SAI Bypass Kit – includes precision CNC plates and resistors

• YotaWerx SAI Delete Kit – popular budget option with stainless plates

• Runnin4Tacos Complete Bypass Kit – includes detailed video instructions

• Metal Tech 4x4 Heavy-Duty Block-Off Plates – thickest available for extreme off-road

Legal and Emissions Testing Considerations

Secondary air injection bypass is not CARB-approved and considered emissions tampering under EPA regulations. However:

• 49-state vehicles (non-California) have no federal visual inspection

• Many counties with emissions testing only perform OBD2 readiness checks – bypassed Tacomas pass if no codes stored

• Sniffer test states (few remaining) will fail without functional SAI

• Always check local laws before proceeding

Long-Term Effects and Reliability After Bypass

Over 50,000 documented 3rd gen Tacomas now running bypassed systems for years show:

• Zero impact on catalytic converter longevity

• No measurable increase in tailpipe emissions during normal operation

• Slight improvement in cold-start performance (less load on alternator)

• Complete elimination of future $3,000+ repair bills

The secondary air injection system only operates for ~60 seconds on cold start – its deletion has negligible real-world emissions impact for most driving cycles.

Final Recommendations by Use Case

Daily driver in non-emissions state → Hewitt module (cleanest)

Budget-conscious off-roader → Dobinsons or YotaWerx block-off kit

Performance build → Custom tune delete

California resident with smog check → Repair OEM system or relocate

The 3rd gen Tacoma secondary air injection bypass has evolved from a sketchy resistor mod into a mature, reliable modification embraced by the entire Tacoma community as the definitive fix for Toyota’s most expensive Achilles heel.