How to Eliminate Check Engine Light (P0420) with an O2 Sensor Spacer

How to Eliminate Check Engine Light (P0420) with an O2 Sensor Spacer

How to Eliminate Check Engine Light (P0420) with an O2 Sensor Spacer

If you’ve ever dealt with the dreaded P0420 check engine light, you know how frustrating it can be. Mechanics often recommend replacing the catalytic converter, which can cost hundreds or even thousands of dollars. But there’s a smarter, more affordable solution that many car owners are using today: an O2 sensor spacer with a mini catalytic converter.

🔍 What Is the P0420 Code?

P0420 is one of the most common diagnostic trouble codes (DTCs). It means:

“Catalyst System Efficiency Below Threshold (Bank 1)”

In simple terms, your vehicle’s onboard computer (ECU) thinks your catalytic converter isn't doing its job properly — even if the engine runs fine.

⚠️ Why Does the P0420 Code Happen?

There are many reasons this code might appear:

  • You’ve installed aftermarket exhaust parts

  • Your catalytic converter is aging but not fully failing

  • You’re using high-flow or performance parts

  • You’ve replaced the O2 sensor or removed it temporarily

  • You have an engine tune that changes fuel ratios

✅ The Affordable Fix: O2 Sensor Spacer with Mini Cat

Instead of replacing your catalytic converter, you can use an O2 sensor spacer — a simple, bolt-on adapter that moves your downstream (secondary) O2 sensor slightly out of direct exhaust flow.

Even better: when paired with a mini catalytic converter built into the spacer, it mimics the behavior of a healthy exhaust system, reducing false P0420 codes and eliminating the check engine light in many cases.

🛠️ How Does It Work?

  • The spacer screws into your exhaust or catalytic pipe in place of the O2 sensor.

  • Your O2 sensor then screws into the spacer’s end, sitting further back from exhaust gases.

  • The built-in mini cat helps clean up the exhaust gases right before they hit the sensor — tricking your ECU into thinking your emissions system is functioning correctly.

🔧 Easy to Install, No Cutting or Welding

  • Thread: M18 x 1.5 (fits most vehicles)

  • Available in straight, 45°, and 90° configurations

  • Install time: ~10 minutes with basic hand tools

🚗 Where to Buy One

We stock high-quality stainless steel O2 sensor spacers with mini catalytic converters in multiple configurations:

👉 Shop O2 Sensor Spacers at CodeFixParts.com
All orders include free U.S. shipping.

⚠️ Disclaimer:

These products are intended for off-road or racing use only. They are not legal for use on public roads in certain states or countries. Always check your local emissions regulations.

Back to blog