Mini catalytic converter
O₂ sensor spacers
A stainless steel M18 × 1.5 spacer with a real catalyst element inside, for catalyst efficiency codes after a decat, high-flow cat or exhaust change. Local stock, shipped across South Africa.
- ✓ Stainless steel
- ✓ Contains a catalyst element
- ✓ Ships from Gauteng
- ✓ Guest checkout
A mini catalytic converter O₂ sensor spacer is a threaded adapter that moves your downstream oxygen sensor 58 mm out of the direct exhaust stream, into a chamber holding a miniature catalyst element. The sensor then reads a damped, delayed gas sample, its signal trace flattens, and the ECU's catalyst efficiency monitor stops setting P0420 or P0430.
It changes what the sensor reports. It does not repair a catalytic converter and it does not reduce tailpipe emissions — and if an exhaust leak, a lazy sensor or a misfire is the real cause, a spacer only hides a different problem.
How it works
Your ECU judges the catalytic converter by comparing two oxygen sensors. Here is what it sees in each case.
Upstream and downstream oxygen sensor traces, before and after fitting the spacer.
Work out whether you need one
These guides are written to be useful even if the answer is that you should not buy a spacer at all.
P0420 Code: What It Means and How to Fix It
P0420 means catalyst efficiency below threshold on Bank 1. Here is what sets the code, every real cause ranked, and how to fix it without wasting money.
Read →P0430 Code: Bank 2 Catalyst Efficiency Explained
P0430 is catalyst efficiency below threshold on Bank 2. Learn how to identify Bank 2 on your V6 or V8, diagnose the right side, and what two banks means.
Read →How to Install an O₂ Sensor Spacer
Step-by-step guide to fitting a mini catalytic converter O₂ sensor spacer to the downstream oxygen sensor, including torque, wiring and the drive cycle.
Read →Will an O₂ Sensor Spacer Fit My Car?
How to check whether an M18 × 1.5 O₂ sensor spacer fits your car: confirm the sensor thread, measure clearance for 58 mm, check wire length and sensor count.
Read →O₂ Sensor Spacer vs a New Catalytic Converter
O₂ sensor spacer vs a new catalytic converter: what each one actually does, cost and fitting time compared, and how to pick the right fix for a P0420.
Read →Check Engine Light After a Decat: What Now?
Check engine light after a decat, straight pipe or downpipe? Why the P0420 appears, what it does to fuelling, and the four ways to deal with it, ranked.
Read →Common questions
What is a mini catalytic converter?
A mini catalytic converter — also called an O₂ sensor spacer or lambda spacer — is a threaded adapter that sits between the exhaust bung and the downstream oxygen sensor. It holds the sensor out of the direct exhaust stream inside a small chamber containing a miniature catalyst element, which flattens the sensor signal the ECU uses to judge catalyst efficiency.
Where can I buy a mini catalytic converter in South Africa?
MiniCats SA holds local stock in Johannesburg, Gauteng and ships nationwide via The Courier Guy. The spacer is R199, with delivery at R99 standard (2–4 business days) or R149 express (next business day).
Will a spacer fix my P0420 code?
It resolves many P0420 cases by changing what the downstream sensor reports. It will not help if the real cause is an exhaust leak, a failing oxygen sensor or an engine misfire, and it does not repair a catalytic converter.