Mini Cat O₂ Sensor Spacers: What They Change, and What They Don’t
A mini cat (also sold as a “mini catalytic converter”) is an O₂ sensor spacer — an M18 × 1.5 stainless-steel adapter, 58 mm long, that repositions your downstream oxygen sensor. It is for cars already running an aftermarket, high-flow or motorsport exhaust setup, and for diagnosing catalyst efficiency codes. It does not repair a catalytic converter or reduce emissions. Our sister business MiniCats SA sells them online and over the counter in Selby, Johannesburg.
A Threaded Adapter That Moves the Sensor
The spacer screws into the exhaust bung where your downstream oxygen sensor normally sits. Your own sensor then screws into the spacer, which holds it 58 mm further out of the direct exhaust stream, inside a small chamber containing a miniature catalyst element.
Because the sensor now samples a damped, delayed gas sample rather than the raw stream, its output trace flattens. That is the pattern the ECU reads as a healthy converter, so in many cases the catalyst efficiency monitor stops setting P0420 or P0430. It changes what the sensor reports — nothing else.
- Thread: M18 × 1.5
- Length: 58 mm · Diameter: 16 mm
- Material: stainless steel
- Contains a miniature catalyst element
- Downstream sensor position only
- Oxygen sensor not included
What This Part Does — and What It Doesn’t
An O₂ sensor spacer changes what your downstream oxygen sensor reports. It does not repair a catalytic converter and it does not reduce what comes out of your tailpipe. If an exhaust leak, a lazy sensor or a misfire is the real cause of your code, a spacer only hides a different problem.
Removing or bypassing a functioning catalytic converter on a road-going vehicle may affect its roadworthy status and emissions compliance in South Africa. This part is sold for motorsport, off-road and diagnostic use, and it is the buyer’s responsibility to confirm what is permitted for their vehicle and use case.
It fits the downstream sensor only — the one after the converter. Fitted upstream it will cause running problems. A V6 or V8 with two banks needs one per bank.
Sold by MiniCats SA, a sister business of EC Recycling that trades from the same Selby premises. Your order, payment and delivery are handled by MiniCats SA.
Sometimes the Answer Is Don’t
A spacer addresses the catalyst efficiency monitor. It does nothing for the faults that commonly set the same code. If your converter is still fitted and actually working, diagnose the code properly first — you may be buying the wrong part.
MiniCats SA publishes guides written to be useful even if the answer is that you should not buy a spacer at all:
- P0420 explained — every real cause, ranked
- Spacer vs a new catalytic converter
- Will it fit my car? Thread, clearance and wiring
EC Recycling buys scrap catalytic converters for recycling. Nothing on this page is advice to remove a catalytic converter that is fitted and working.
Order Online, or Collect in Johannesburg
Same part either way. Current price, stock and delivery options live on the MiniCats SA product page.
Order Online
Buy direct from MiniCats SA and have it couriered anywhere in South Africa. Stock is held locally in Johannesburg; standard delivery is 2 to 4 business days.
Order on minicats.co.za Changes what the sensor reports. Does not repair a catalytic converter or reduce emissions. Sold for motorsport, off-road and diagnostic use.Collect in Johannesburg
MiniCats SA sells them over the counter at Unit 1, 14 John Street, Selby, Johannesburg, 2001, the same premises as our Johannesburg branch. Phone 084 306 6660 first to confirm stock and collection times.
Directions & Hours Changes what the sensor reports. Does not repair a catalytic converter or reduce emissions. Sold for motorsport, off-road and diagnostic use, by MiniCats SA, not by EC Recycling.