P0420 / P0430 Fix for Nissan Altima, Maxima & Murano

P0420 or P0430 is one of the most common check engine codes on the Nissan Altima, Maxima, and Murano, usually from an aging catalytic converter that still runs fine but trips the light. Before you spend $600 or more on a new cat, this is the part to try first.

The Fix: 90° O2 Sensor Spacer

The Brockett Built 90° O2 sensor spacer threads into the downstream (rear) O2 bung and moves the sensor out of the direct exhaust stream, so the ECU reads a clean signal and stops throwing the catalyst-efficiency code. CNC-machined for the M18x1.5 thread, a direct fit for Nissan downstream sensors.

• About a 10-minute install. Clear codes and drive a readiness cycle.
• Downstream (rear) sensors only, never the upstream sensor.

One Spacer or Two?

• Altima 4-cylinder (QR25DE): single bank, one spacer (P0420).
• Altima V6, Maxima & Murano (VQ35 / VQ35DE): dual bank. If you also have P0430, grab the 2-Pack.

FAQ

Will it affect performance or fuel economy?
No. The downstream sensor only monitors cat efficiency, it doesn't control fuel trim, so your tune and mileage are unaffected.

Legal note: designed for modified/off-road use. Check local emissions laws.

Get the 90° O2 Sensor Spacer: $42 single / $84 2-Pack →

Machined by Brockett Built in central Illinois. Ships same or next business day. 30-day fitment guarantee.