90° O2 Sensor Spacer — Mini Cat CEL Fix for P0420/P0430 (M18x1.5) | Brockett Built

90 Degree O2 Sensor Spacer — Mini Catalytic Converter CEL Fix

The Brockett Built 90° O2 sensor spacer (also called a mini catalytic converter spacer, O2 defouler, or bung extender) eliminates P0420 and P0430 check engine light codes caused by low catalyst efficiency — a common issue after installing headers, high-flow cats, or a catless mid-pipe.

⚠️ For secondary (downstream) O2 sensor bungs ONLY. This spacer installs in the rear O2 bung after the cat — never on the primary/upstream sensor.

🏁 FOR OFF-ROAD & COMPETITION USE ONLY. This product is intended for off-road, competition, and racing vehicles. It is not intended for use on emissions-controlled vehicles operated on public roads. Buyer is responsible for compliance with all federal, state, and local laws.

Machined for a precise M18x1.5 thread (standard O2 sensor thread) and built to survive full exhaust temps. Ships same or next business day.

🔥 Key Benefits

• Fixes P0420 & P0430 (catalyst efficiency below threshold) codes
• Works with headers, high-flow cats, and catless setups
• Restores smooth idle and eliminates false CEL trips
• Quick, bolt-on install — no tuner or ECU flash required
• CNC-machined, stainless internal, full-temp rated

🚗 Confirmed Fitment

Fits any vehicle with an M18x1.5 downstream O2 sensor, including but not limited to:

• Lexus GX470 (2003–2009) — 4.7L 2UZ-FE
• Lexus GX460 (2010+) — 4.6L 1UR-FE
• Toyota 4Runner V8 (2003–2009) — 4th gen
• Toyota 4Runner V6 (2003+) — 1GR-FE
• Toyota Tundra / Sequoia / Land Cruiser (2UZ / 3UR / 1UR)
• Toyota Tacoma (2005+) — 1GR-FE / 2TR-FE
• FJ Cruiser (2007–2014)
• Most Honda, Nissan, Subaru, Ford, GM, Jeep, and Ram gas engines with M18x1.5 O2 threads

Not sure if your vehicle fits? Message us with your year/make/model and we'll confirm.

🔧 Fitment Guides by Vehicle

Deep-dive install guides with bank counts and code details for the most common vehicles we see:

• GM & Ford: Chevy Silverado / GMC Sierra 5.3 · Ford F-150
• Ram & Mopar: Ram 1500 5.7 HEMI · Jeep Wrangler 4.0 · Jeep Grand Cherokee · Dodge Durango / Charger / Challenger
• Toyota & Lexus: 4Runner V8 · Lexus GX470 / GX460 · Tacoma · Tundra / Sequoia · FJ Cruiser · Camry · Sienna
• Honda: Accord / Civic · CR-V / Pilot / Odyssey
• Nissan: Frontier / Xterra / Pathfinder · Altima / Maxima / Murano
• Subaru: WRX / STI

⚙️ How It Works

The 90° spacer threads into your factory secondary (downstream/rear) O2 sensor bung, then the sensor threads into the spacer. The offset geometry and internal restrictor slow the exhaust gas reaching the sensor tip, letting the rear O2 read a \"clean\" signal — so the ECU stops throwing catalyst-efficiency codes.

This is the fix when:

• Running long-tube or shorty headers
• Running a catless mid-pipe or test pipe
• Using high-flow catalytic converters
• Dealing with an aging OEM cat that still functions but trips codes

🚨 Supported OBD-II Codes

Bank 1: P0420, P0421, P0422, P0423, P0424
Bank 2: P0430, P0431, P0432, P0433, P0434

🔧 Installation

• Install on the secondary (downstream/rear) O2 sensor bung ONLY
• Do NOT install on the primary/upstream (front) sensor — it controls fuel trim and will cause driveability issues
• Thread spacer into existing O2 bung, then thread sensor into spacer
• Anti-seize on threads recommended
• Tighten snug — do not overtighten (25–30 ft-lbs)
• Clear codes with an OBD-II scanner and drive a full readiness cycle

⚠️ Important Notes

• Off-road, competition, and racing use only — not for use on emissions-controlled vehicles on public roads. Buyer is responsible for compliance with all applicable laws
• Secondary (downstream) O2 bungs only — never install on the primary/upstream sensor
• V8 / dual-bank vehicles need 2 spacers (one per bank) — grab the 2-Pack V8 Kit and save
• Inline-4 / V6 single-bank vehicles need 1 spacer
• Does not repair a physically failed catalytic converter
• O2 sensor itself must be in working order

❓ FAQ

Can I install this on the front (upstream) O2 sensor?
No — this is for the secondary (downstream) bung only. The upstream sensor controls your fuel trim; putting a spacer there will cause rough running and new codes.

Will this clear my P0420 code?
Yes — if the code is caused by low catalyst efficiency after headers, catless pipes, high-flow cats, or an aging cat. It won't fix codes caused by a bad O2 sensor itself or an exhaust leak.

Do I need one or two?
V8s and other dual-bank engines need two (one per bank) — that's what the 2-Pack V8 Kit is for. Single-bank engines need one.

What thread size is this?
M18 x 1.5 — the industry-standard O2 sensor thread used on virtually every gas OBD-II vehicle.

Does it work with wideband O2 sensors?
It's designed for the narrowband downstream sensor. Do not install on a wideband tuning sensor.

Will it affect fuel economy or performance?
No — the downstream sensor only monitors cat efficiency, it doesn't control fuel trim. Your tune is unaffected.

How fast does it ship?
Same or next business day from our central Illinois shop, USPS First Class.

🔩 Complete Your Exhaust

Most spacer customers are upgrading the rest of the system too. Everything below is TIG-welded 304 stainless, built to order in our Illinois shop:

• 4.7L 2UZ-FE Mid-Length Headers — GX470 & 4th Gen 4Runner V8
• GX470 Y-Pipe · 4Runner V8 Y-Pipe · GX460 Y-Pipe
• Modular Catback System — GX470, GX460 & V8 4Runner

Designed and machined in-house by Brockett Built. Backed by our 30-day fitment guarantee — if it doesn't fit or doesn't clear your code, we'll make it right.