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MiniCatsSA O₂ sensor spacers
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Free collection: Unit 1, 14 John Street, Selby, Johannesburg 2001 Mon–Fri 08:00–16:30 · Sat 08:00–13:30 · Sun closed 084 306 6660 [email protected]

P0420 · P0430 catalyst efficiency codes

Mini catalytic converter O₂ sensor spacer

A stainless steel M18 × 1.5 spacer with a real catalyst element inside, for catalyst codes after a high-flow cat, downpipe or exhaust change. Fits on the downstream sensor with a 22 mm socket — no welding, no tuning.

R350.00 per spacer · sensor not included
In stock — 69 available
Buy the MiniCat Will it fit my car?
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Mini catalytic converter O₂ sensor spacer in brushed stainless steel, shown with the ceramic honeycomb catalyst element and the perforated restrictor disc that sit inside it M18 × 1.5 thread 58 mm long Catalyst element inside
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Collect freeSelby, Mon–Fri 08:00–16:30
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What it is

A small part that changes what one sensor reports

In one paragraph

A mini catalytic converter O₂ sensor spacer is a 58 mm threaded adapter that moves your downstream oxygen sensor 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 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 — if an exhaust leak, a lazy sensor or a misfire is the real cause, a spacer only hides a different problem.

Usually a good fit when…

  • P0420 or P0430 appeared after a high-flow cat, downpipe or on an ageing catalyst
  • Fuel trims, misfires and the upstream sensor all check out
  • There are no exhaust leaks ahead of the downstream sensor

Not the fix when…

  • There are misfire, fuel-trim or upstream sensor codes too
  • The downstream sensor itself is slow or faulty
  • The cat has been removed entirely — a spacer may not be enough on a full decat
  • You need the vehicle to meet an emissions test
Diagnose a P0420 first

How it works

What your ECU sees, before and after

The engine computer judges the catalytic converter by comparing the oxygen sensors before and after it. When the two signals look alike, it sets the code.

FIG. 1 — SENSOR SIGNALS
How the MiniCat oxygen sensor spacer works Three panels compare downstream oxygen sensor signals. With a healthy catalytic converter the downstream trace stays flat and the readiness monitor passes; with the converter removed or worn out both traces oscillate and mirror each other, so the ECU sets fault code P0420 or P0430; with the MiniCat spacer fitted, the vehicle's existing downstream sensor sits 58 mm back inside a small chamber holding a ceramic catalyst element and a perforated restrictor disc, so it samples damped gas and its trace flattens again. The spacer changes what the sensor reports; it does not repair a catalytic converter or reduce tailpipe emissions. 1 Healthy catalytic converter upstream O2 downstream O2 exhaust flow catalytic converter upstream signal downstream signal Downstream trace stays flat - monitor passes 2 Cat removed or worn upstream O2 downstream O2 no active catalyst upstream signal downstream signal Traces mirror - ECU sets P0420 / P0430 3 With the MiniCat spacer upstream O2 your existing O2 sensor MiniCat spacer catalyst element inside 58 mm no active catalyst upstream signal downstream signal Sensor reads a damped sample - monitor passes The spacer changes what the sensor reports. It does not repair a catalytic converter or reduce emissions.

Swipe to see all three

Upstream and downstream oxygen sensor traces: a healthy cat, a removed cat, and the same car with the spacer fitted.

In the box

Machined stainless body, catalyst insert, restrictor disc

One M18 × 1.5 spacer: male thread into the exhaust bung, female thread for your own sensor, with the catalyst element and restrictor disc inside.

FIG. 2 — EXPLODED VIEW
Mini catalytic converter oxygen sensor spacer, exploded view Exploded assembly drawing of the M18 x 1.5 stainless steel oxygen sensor spacer. It shows the 58 mm body in cross-section with its female bore and male thread, the ceramic honeycomb catalyst element and the seven-hole perforated restrictor disc that sit inside it, and the vehicle's own oxygen sensor, drawn as a dashed ghost because it is not supplied. What is in the box Exploded view — every part supplied, and the one part that is not. = where those parts sit inside the body 58 mm M18 × 1.5 Ceramic honeycomb catalyst sits inside the body chamber Perforated restrictor disc 7 drilled holes meter the gas sample Your existing O2 sensor NOT INCLUDED re-use the one already on your car Female M18 × 1.5 bore your O2 sensor screws in here Stainless steel body, sectioned Male M18 × 1.5 thread screws into the exhaust bung

Swipe to see every part

The spacer body, the ceramic honeycomb catalyst element and the perforated restrictor disc. Your oxygen sensor, drawn dashed, is re-used and not supplied.
Thread
M18 × 1.5
Length
58 mm
Body
Stainless steel
Diameter
16 mm

Your oxygen sensor is not included. You reuse the downstream sensor already on the car.

Male thread of the mini catalytic converter spacer, close-up
Male threadScrews into the exhaust bung where the sensor was.
Catalyst element of the mini catalytic converter spacer, close-up
Catalyst elementCeramic honeycomb inside the chamber.
Restrictor disc of the mini catalytic converter spacer, close-up
Restrictor discSeven drilled holes meter the gas sample.

Installation

Fitted in 30–60 minutes with a sensor socket and a torque wrench

Unscrew the downstream sensor, screw the spacer in, refit the sensor, clear the code. Here is the job at a glance.

Full step-by-step guide
30–60 minutes
Typical time, including lifting the car
22 mm
Slotted O₂ sensor socket
40–50 Nm
Usual sensor torque — check your manual
Downstream
Post-cat sensor only · one spacer per downstream sensor
  1. Find the downstream sensor

    Find the downstream sensor

    The one after the catalytic converter — never the upstream one.

  2. Remove it

    Remove it

    Penetrating oil, then a slotted 22 mm socket so the wire runs through the slot.

  3. Fit the spacer

    Fit the spacer

    Anti-seize on the threads, start it by hand, then refit the sensor into it.

  4. Clear and drive

    Clear and drive

    Torque both joints, check wire slack, clear the code and complete a drive cycle.

Compatibility

Will it fit my car?

Most petrol cars with a downstream oxygen sensor use the M18 × 1.5 thread this spacer is made for. Four quick checks confirm it.

Run the full fit check

  1. The sensor thread is M18 × 1.5

    The common size on most petrol cars. If a 22 mm (7/8") socket fits the sensor hex, it almost always is.

  2. There is 58 mm of clearance

    The spacer is 58 mm long overall and the sensor sits further out. Check it will not touch a heat shield, subframe or the floor.

  3. The wire has slack

    The loom has to reach the extra distance without pulling on the connector.

  4. One spacer per downstream sensor

    Four-cylinder engines normally have one downstream sensor. V6 and V8 engines usually have two, one per bank, and need two spacers.

FIG. 3 — FIT CHECK
Fitment check for the oxygen sensor spacer Four checks to make before ordering: confirm the sensor thread is M18 x 1.5, allow 58 mm of clearance for the spacer's length, make sure the sensor lead still reaches its connector without being pulled tight, and count one spacer for every downstream oxygen sensor - one on an inline four, two on a V6. Will it fit your car? Four quick checks before you order 1 THREAD caliper or thread gauge M18 x 1.5 18 mm diameter, 1.5 mm pitch Measure the thread on your old sensor, or read its part number. 2 CLEARANCE underbody heat shield exhaust pipe swing room 58 mm the spacer’s own length The spacer is 58 mm long: allow the room. Check nothing fouls. 3 WIRE REACH enough slack stretched tight The lead must reach without being pulled tight. 4 HOW MANY cat downstream sensor Inline 4·1 spacer V6·2 spacers One spacer per downstream sensor — fitted after the cat.

Swipe to see all four checks

Thread, clearance, wire slack and how many spacers: the four things to check before you order.

Delivery & collection

Collect free in Selby, or have it couriered

Collection is always free and usually the quickest. Courier delivery is priced live by The Courier Guy for your exact address at checkout.

RecommendedFree

Collect from PGM Recycling

  • Unit 1, 14 John StreetSelby, Johannesburg 2001
  • Monday – Friday 08:00 – 16:30
    Saturday 08:00 – 13:30
    Sunday Closed
  • 084 306 6660 — call ahead outside these hours
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Courier delivery

  • NationwideDelivered anywhere in South Africa by The Courier Guy
  • Live price at checkoutCourier delivery is priced live by The Courier Guy for your exact address at checkout. That live price is the only delivery charge.
  • Tracking by emailYour tracking reference is emailed once the parcel is handed to The Courier Guy

If a live courier price cannot be had for your address, checkout offers free collection instead. Expected delivery dates are shown with each price.

Guides

Work out whether you need one

Written to be useful even if the answer is that you should not buy a spacer at all.

All guides

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 the guide

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 the guide

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 the guide

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 the guide

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 the guide

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 the guide

FAQ

Common questions

Straight answers, including the ones that talk you out of buying.

All questions
What is a mini catalytic converter?

A mini catalytic converter — also called an O₂ sensor spacer or lambda spacer — is a threaded adapter, 58 mm long overall, 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 with a miniature catalyst element, which flattens the signal the ECU uses to judge catalyst efficiency.

Where can I buy a mini catalytic converter in South Africa?

From MiniCats SA. Stock is held in Johannesburg. The spacer is R350.00. You can collect it free from PGM Recycling, Unit 1, 14 John Street, Selby, Johannesburg 2001 (Mon–Fri 08:00–16:30 · Sat 08:00–13:30 · Sun closed), or have it couriered anywhere in South Africa, priced live by The Courier Guy for your exact address at checkout.

How long does it take to fit?

Plan on 30–60 minutes. About 15 minutes for the swap itself — allow longer to lift the car safely or free a seized sensor. You need a 22 mm (7/8") slotted O₂ sensor socket, anti-seize and a torque wrench. It goes on the downstream sensor only.

Will a spacer fix my P0420 code?

It resolves many P0420 and P0430 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 a misfire, and it does not repair a catalytic converter or reduce emissions.

Ready to clear that catalyst code?

R350.00 per spacer. Collect free in Selby or courier nationwide — pay securely by card or instant EFT.

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