Questions, answered straight

A threaded stainless steel adapter that fits between the exhaust bung and your downstream oxygen sensor. It is 58 mm long and holds the sensor further out of the exhaust stream, in a small chamber with a miniature ceramic catalyst element and a drilled restrictor disc. The sensor then reads a damped, delayed gas sample, which flattens the signal the ECU uses to judge catalyst efficiency, so the monitor can stop setting P0420 or P0430. It changes what the sensor reports; it does not repair a catalytic converter.

The MiniCats SA mini catalytic converter spacer is R350, oxygen sensor not included. Collection from PGM Recycling in Selby, Johannesburg is free. Courier delivery is priced live by The Courier Guy for your exact address at checkout, and that price is exactly what you pay. Imported listings can look cheaper before you add international shipping, the exchange rate, and any customs and clearing charges on arrival.

No — the oxygen sensor is not included. You reuse the downstream sensor already on your car: it unscrews from the exhaust, the spacer goes into the bung, and the sensor threads into the spacer. If your sensor is old, contaminated or already setting its own fault codes, replace it first; a spacer cannot make up for a sensor that has stopped responding properly.

It is 58 mm long and 16 mm in diameter, made of stainless steel, and weighs about 0.2 kg. The thread is M18 × 1.5: the spacer screws into the exhaust bung where the sensor was, and the sensor screws into the spacer. Inside are a ceramic honeycomb catalyst element and a drilled restrictor disc that meters the gas sample.

Yes, it is in stock. Stock is held in Johannesburg, Gauteng rather than overseas, so there is no import wait and no customs step. The product page shows the live count before you order.

The part lives in the exhaust stream and sees heat cycling, moisture and road salt near the coast. Mild steel spacers corrode from the inside, which seizes the sensor into the spacer and can leave you cutting a rusted assembly out later. Stainless costs a little more to make and does not do that.

Not on every car. A plain hollow spacer only moves the sensor out of the gas stream. One with a miniature catalyst element also treats the small sample of gas that reaches the sensor, which is why it can work on cars where a hollow tube alone does not. Neither type is guaranteed to clear a code, and on a full decat either can fail. If a listing does not say, assume it is hollow.

No. A spacer recesses the downstream oxygen sensor out of the direct exhaust stream so its signal flattens and the catalyst monitor stops setting a fault. It does not repair the catalytic converter and it does not reduce what comes out of your tailpipe. Only a working catalytic converter does that.

You have three realistic routes: import from an overseas marketplace, buy from a local classifieds or marketplace listing, or buy from a South African specialist holding local stock. MiniCats SA is the third of those — the spacer is R350 and held in stock in Johannesburg, Gauteng. You can collect it free from PGM Recycling in Selby, or have The Courier Guy deliver it nationwide.

A spacer does not fix P0420 in the sense of repairing anything. It recesses the downstream oxygen sensor out of the direct exhaust stream so the signal it reports flattens out, which can allow the catalyst monitor to pass and the light to stay off. It changes what the sensor reports; it does not repair a catalytic converter and does not reduce what comes out of your tailpipe. It works on many cars with a high-flow or ageing catalyst. On a full decat or a gutted, badly failed cat it sometimes works, but not reliably — there is no guarantee.

No, and treating it as automatic is the single most expensive mistake people make with this code. The ECU does not measure the catalyst directly; it infers catalyst health from two oxygen sensor signals. An exhaust leak between the manifold and the downstream sensor, a slow-responding sensor, an ongoing misfire, or oil and coolant contamination will all produce the same conclusion. Rule those out before buying a converter.

They are the same fault on different sides of the engine. P0420 refers to Bank 1, which is the cylinder bank containing cylinder number one, and P0430 refers to Bank 2. A four-cylinder inline engine only has Bank 1, so it can only set P0420. A V6, V8 or flat engine has both banks and can set either code, or both. See the guide on P0430 for bank-specific diagnosis.

In most cases yes, at least in the short term. P0420 is an emissions monitor fault, not a mechanical failure warning, so the engine will usually run normally and the light stays steady rather than flashing. The exception is when P0420 appears alongside misfire codes or a flashing engine light, because raw fuel reaching a hot catalyst can melt the substrate and turn a cheap repair into an expensive one. If the light is flashing, stop driving and diagnose it.

Clearing the code with a scan tool resets the readiness monitors, and the catalyst monitor only runs once its enabling conditions are met, typically a cold start followed by a period of steady cruising. That usually takes somewhere between one and several drive cycles, so the light commonly returns within a few days of normal driving. If nothing has actually changed on the car, expect it back. If it takes weeks to return, the fault is marginal rather than severe.

Sometimes. Most ECUs will switch the lamp off on their own after roughly three consecutive drive cycles in which the catalyst monitor runs and passes, and the stored code eventually ages out after about forty warm-up cycles. That means a code triggered by a one-off event such as a bad tank of fuel or a brief misfire can disappear without any intervention. A code caused by a worn catalyst or an exhaust leak will not clear itself, because the condition is still there every time the monitor runs.

Only if there is evidence pointing at them, such as a slow switching upstream sensor on live data, a sensor heater circuit code, or a sensor that has never been replaced on a high-mileage car. Fitting sensors blindly is a common way to spend money and still have the light on. Look at the live data first: the upstream sensor should be switching rapidly between roughly 0.1 V and 0.9 V, and the downstream one should be comparatively slow and flat.

Frequently, yes. Budget universal converters often contain less precious metal and a smaller substrate than the original part, so they store less oxygen and the monitor still sees the downstream trace tracking the upstream one. It is common for a new cheap cat to run clean for a few thousand kilometres and then set P0420 again. If you are replacing the converter, match or exceed the original specification rather than buying on price alone.

The code itself does not. The ECU does not change fuelling strategy because the catalyst monitor failed, so on its own P0420 has no measurable effect on economy or performance. What you can feel is a physically blocked or collapsed catalyst, which restricts exhaust flow and causes a lack of power at high revs and poor economy. If you have both the code and a genuine loss of power, suspect a blockage and check exhaust back pressure.

Bank 2 is the cylinder bank that does not contain cylinder number one. There is no universal left or right rule, because manufacturers number cylinders differently and a transverse V6 can have Bank 1 at the front or at the back depending on the engine. The only reliable method is to find cylinder one for your specific engine in the workshop manual or by the firing order stamped on the cam cover, then work out which bank the other cylinders sit on.

Not under normal circumstances. An inline four has a single cylinder bank, so it only has Bank 1 and can only set P0420. If a scan tool reports P0430 on a four-cylinder car, either the tool is misreading the code, the code is stored from a generic lookup table rather than the manufacturer database, or the ECU has been flashed with software from a different application. Re-read the codes with a tool that supports the manufacturer-specific protocol before doing anything else.

Two catalytic converters very rarely fail in the same week by coincidence, so both codes together usually point at something common to both banks rather than at two dead cats. Look upstream first: a misfire, a fuelling problem, a faulty mass airflow reading, low fuel pressure, or oil and coolant contamination reaching both banks. On a high-mileage engine both converters ageing out together is possible, but it is the last thing to conclude, not the first.

The two banks do not live identical lives. One bank often runs slightly hotter because of where it sits relative to the radiator and the turbo or manifold routing, one side may have had an injector or coil problem years ago that partly cooked its converter, and exhaust manifold gasket leaks are usually on one side only. Uneven ageing between banks is completely normal, which is why single-bank codes are more common than paired ones.

Yes, and on a V engine it is one of the most useful tests you have, provided the connectors and wire lengths allow it. Swap the two downstream sensors between banks, clear the codes, and drive until the monitor runs again. If the fault follows the sensor to the other bank, you have a sensor problem. If the code stays on Bank 2, the problem is that bank's exhaust or converter.

It can. Some V engines have the two banks joined into a single pipe after the converters, and a few designs share a section before them. Any leak in a shared section, or in the crossover on an engine that has one, can influence both banks at once and produce confusing results. Before condemning a converter, work out on your car exactly where the two exhaust paths merge and check every joint upstream of the Bank 2 downstream sensor.

Sometimes, but not reliably — there is no guarantee. A spacer works on many cars with a high-flow or ageing catalyst, but on a badly failed, gutted or removed catalyst the downstream sensor sees almost the same gas as the upstream sensor, and the spacer may not damp it enough. This MiniCat already has a catalyst element, which gives it a better chance than a plain hollow spacer, not a certainty. If it does not clear the code, the car needs a different approach, such as an ECU tune or a new catalytic converter.

It varies enormously by vehicle, so get two written quotes before you decide. An original part from a dealer, an aftermarket universal cat welded in, and a high-flow cat are three very different prices, and fitting labour is charged on top. Ask each quote to state the part, the labour and whether the old unit is traded in.

Be careful. You cannot see substrate condition from outside, a used cat may already be part-poisoned, and catalytic converter theft in South Africa means some second-hand stock has a questionable history. If you go this route, buy from a dealer who will give you an invoice with the part identified.

It can be. A high-flow cat still contains a real catalyst element, so it does real emissions work, and it usually costs less than an original-equipment unit. The trade-off is that its lower cell density can be enough to keep the downstream sensor trace too active, so some cars still log a P0420 afterwards.

Yes, and many people do. A spacer is cheap enough to use as a stopgap while you save for the proper repair, provided you have already ruled out an exhaust leak, a lazy oxygen sensor and a misfire. Just do not treat a quiet dashboard as proof the problem went away.

The ECU compares the upstream and downstream oxygen sensor signals. With no catalyst in between there is nothing buffering oxygen, so the downstream sensor starts mirroring the upstream one. The catalyst efficiency monitor reads that as a failed cat and sets P0420, or P0430 for bank 2.

Anywhere from the first drive to a few days. The catalyst monitor only runs once its enable conditions are met — warmed up, steady cruise, stable fuelling, enough fuel in the tank on some cars. Most people see it within one to three complete drive cycles.

It can. Many ECUs apply a slow fuel trim correction based on the downstream sensor, and with no catalyst that correction is being made from a signal it was never designed to see. Some cars also drop out of certain adaptive strategies while a fault is stored. The effect is usually small but it is not always zero.

If a tune is available for your ECU, a remap with the rear oxygen sensor monitor disabled is the cleanest technical solution — the ECU stops running the test at all, so there is nothing to fool. A spacer is the cheap route when no tune exists, when you do not want to remap, or when you want something reversible.

Sometimes, but not reliably — there is no guarantee. A spacer with a miniature catalyst element damps and delays the gas the sensor samples, and that works on many cars with a high-flow or ageing catalyst. A full decat or straight pipe is the hardest case: with no catalyst anywhere in the system the spacer is doing all the work on its own, and on some cars, especially those with an aggressive monitor strategy, it is not enough. Those cars need a different approach, such as an ECU tune or a catalytic converter.

An emulator is an electronic device that sits between the sensor and the loom and generates or modifies the signal the ECU sees. It is more configurable than a mechanical spacer, but it is also more expensive, needs wiring, and a badly matched emulator can produce a signal the ECU rejects outright. A spacer has nothing to go wrong electrically.

No. Unplugging it sets a circuit fault code and leaves the light on anyway, usually with a heater circuit code alongside it. You have swapped one permanent light for another and lost the diagnostic value of the sensor.

It is a hand-tool job — we rate it easy to moderate. If you can change an oxygen sensor, you can fit this: unscrew the downstream sensor, screw the spacer into the bung, screw the sensor into the spacer, then clear the code. On an older car the hard part is usually freeing a seized sensor, not fitting the spacer. If you would rather not do it yourself, it is the same job as changing an oxygen sensor, so a workshop that does exhaust or sensor work can fit it.

The downstream sensor only — the one fitted after the catalytic converter, closer to the middle or rear of the car. The upstream sensor sits before the cat, usually in or just behind the exhaust manifold. The downstream sensor monitors catalyst efficiency; the upstream sensor controls fuelling.

The engine will run badly. The upstream sensor is the one the ECU uses to trim the air-fuel ratio in real time, so recessing it out of the exhaust stream slows and distorts the signal it depends on. Expect rough running, poor fuel economy and new fuel trim fault codes. Move it to the downstream sensor.

Plan on 30–60 minutes. About 15 minutes for the swap itself — allow longer to lift the car safely or free a seized sensor. On a V6 or V8 with a downstream sensor on each bank you are fitting two spacers, so allow for the second one, which is often the harder to reach.

A slotted 22 mm oxygen sensor socket, a ratchet with an extension, penetrating oil, a wire brush, anti-seize compound, a torque wrench, and a trolley jack with axle stands. An OBD reader is needed to clear the code afterwards and to confirm the monitor has re-run.

Start both by hand and keep them finger-tight until you have checked wire slack and clearance. Then tighten the spacer into the bung first and the sensor into the spacer, with a torque wrench. Usually 40–50 Nm — use the figure in your vehicle manual. Do not guess by feel: exhaust bungs are welded to thin pipe and they can pull out.

Yes on the threads, never on the sensor tip. A thin smear of high-temperature anti-seize on the male threads of the spacer and on the sensor threads makes the next removal far easier. Keep it well away from the sensing element, because contamination will skew or kill the sensor. Many new sensors arrive with compound already applied.

Soak the threads in penetrating oil and leave it, then run the engine to warm the exhaust, shut it off and try again once the pipe is cool enough to touch. The expansion and contraction cycle breaks the corrosion bond. Use a slotted oxygen sensor socket so the wiring passes through the slot and the socket grips all six flats. If the hex starts to round or the bung moves, stop and let a workshop extract it.

It usually does, but check before you tighten anything. The spacer is 58 mm long and moves the sensor further out of the bung, so the loom has to take up that extra distance plus any change in angle. If the wire is tight or pulling on the connector, reroute it or unclip it from its bracket — never stretch it.

On some vehicles with high ground clearance you can reach the downstream sensor from the side, but on most cars you cannot get a socket and ratchet on it. If you do lift the car, use axle stands on a solid level surface. Never work under a vehicle supported only by a jack.

Four things, and all of them are avoidable: an old sensor seized in the bung (soak it in penetrating oil and use a slotted socket); a wire that is too tight once the sensor sits further out on the 58 mm spacer; the spacer fouling a heat shield or the underbody; and an exhaust leak at the new joint — two threaded joints where there was one means two chances to leak. Check wire slack and clearance with both parts finger-tight before you torque anything, and listen for a ticking or hissing leak when you first start the engine.

Clearing the code turns the light off immediately, but the catalyst monitor has to re-run before you know whether the fix held. That takes a full drive cycle, typically a cold start followed by a mix of steady cruising and light town driving over a day or two of normal use. Recheck for pending codes with an OBD reader afterwards.

Most often it means the underlying problem is bigger than the spacer can mask — a badly failed catalyst, an exhaust leak upstream, a lazy sensor or a misfire. It works on many cars with a high-flow or ageing catalyst, but on a full decat or a gutted cat it sometimes works and sometimes does not, and some vehicles use aggressive monitor strategies that a spacer cannot satisfy. Those cars need a different approach, such as an ECU tune or a new catalytic converter. Diagnose the exhaust and sensor before assuming the spacer is at fault.

Four checks settle it: your downstream oxygen sensor has an M18 × 1.5 thread, there is 58 mm of clear space behind the bung for the spacer to stick out into, the sensor wire has slack to reach, and you order one spacer per downstream sensor (a V6 or V8 has two). The M18 × 1.5 thread is used on the large majority of petrol vehicles; check your sensor part number or measure the thread on the old sensor to confirm before ordering.

Yes. Send us the part number from your existing downstream oxygen sensor, with your vehicle's make, model and year, through the contact page, by email to [email protected] or by phone on 084 306 6660. We will tell you whether the M18 × 1.5 spacer fits — including when the answer is no.

No, and we would rather not publish a guessed one. Fitment is determined by the sensor thread and the space available, not by badge or model year, and the same model can use different sensors across markets and engine variants. Checking your own sensor, or its part number, gives a definite answer.

Diesels do not use the same oxygen sensor arrangement as petrol engines and generally do not run a catalyst efficiency monitor comparing pre and post-cat lambda sensors in the same way. If your diesel has a downstream lambda sensor with an M18 × 1.5 thread the part will physically screw in, but it will not address diesel-specific aftertreatment codes such as DPF or SCR faults.

Yes, but you need two spacers — one per sensor. V6, V8 and some flat and V4 engines run two banks with a catalyst and a post-cat sensor on each. Bank 1 sets P0420 and Bank 2 sets P0430, so if you have codes on both banks you are fitting two.

No. The spacer is M18 × 1.5 and will not thread into a smaller bung or accept a smaller sensor. A minority of vehicles, including some motorcycles and small-capacity engines, use M12 × 1.25 or M14 × 1.5 sensors. Confirm your thread before ordering rather than after.

Only if there is genuinely 58 mm of clear space in the direction the sensor points. Lie under the car and picture a 58 mm part screwed in between the bung and the sensor: where would the sensor end up? If it would hit a heat shield, a subframe rail or the floorpan, the part will not work on that vehicle in that position.

Check before ordering. The spacer is 58 mm long and moves the sensor further out of the pipe, so the loom must reach further without tension on the connector. Most vehicles have enough slack once the wire is unclipped from its brackets, but some do not. Never stretch a sensor loom to make it reach.

The fitment question is the same four checks: the M18 × 1.5 thread, 58 mm of clearance, slack in the wire and one spacer per downstream sensor. Whether it will clear the resulting code is a separate question. It works on many cars with a high-flow or ageing catalyst. A full decat, with no catalyst at all, is the hardest case: it sometimes works, but not reliably, and there is no guarantee. The catalyst element in this MiniCat gives it a better chance than a plain hollow spacer, not a certainty.

Give your vehicle details to any parts counter or online parts catalogue and ask for the downstream oxygen sensor for your car, then look at the thread listed in that sensor specification. Almost every sensor listing states the thread size. You can also send us the sensor part number through the contact page.

Then this part is not for your vehicle and we would rather you knew that before ordering. If your thread is M12 or M14, or there is no room behind the bung, no amount of adapting will make this the right part. Contact us with your sensor part number if you want a second opinion before you buy.

If both P0420 and P0430 are set, yes, you need one spacer per bank, because each bank has its own downstream oxygen sensor and its own monitor. If only P0430 is set, one spacer fitted to the Bank 2 downstream sensor is enough. Fitting a single spacer to the wrong bank does nothing at all, which is the most common mistake on V engines.

Most have four: an upstream and a downstream sensor on each bank. They are labelled by bank and by position, so Bank 2 Sensor 1 is the upstream sensor on Bank 2 and Bank 2 Sensor 2 is the downstream one after that bank's catalytic converter. P0430 concerns the comparison between Bank 2 Sensor 1 and Bank 2 Sensor 2, and a spacer only ever goes on a Sensor 2 position.

Yes, and collection is always free. Choose collection at checkout, then collect from PGM Recycling in Selby, Johannesburg, during the opening hours below. We email you when your order is ready. Please bring your order number and ID. Call ahead if you are collecting outside these hours.

Collection is free. Courier delivery is priced live by The Courier Guy for your exact address at checkout, and that live price is the only delivery charge. If no live price can be had for your address, checkout offers free collection from PGM Recycling in Selby instead.

It depends on the address and the service. At checkout The Courier Guy lists the services available for your address, each with its live price and expected delivery dates, so you see both before you pay. Orders ship from Johannesburg; outlying towns and farm addresses can take longer. Once the parcel is handed to the courier you get a tracking reference by email.

Cape Town is a main centre, like Durban, Gqeberha and Bloemfontein, and The Courier Guy delivers there from Johannesburg. At checkout, enter your Cape Town address and you see the services The Courier Guy offers to it, each with its live price and delivery date, so you know both before you pay; the price of the service you choose is exactly what you are charged. Outlying towns and farm addresses generally take longer than main-centre addresses.

Johannesburg, Gauteng. Stock is held locally, so there is no import wait and no customs step.

No. Delivery is within South Africa only.

Checkout runs through PayFast, a South African payment gateway, so you can pay by card or instant EFT. You enter your card or banking details on PayFast's own pages — they never reach our servers.

No. Guest checkout is available: choose quick pay and you still get an emailed order number you can use to track the order. If you prefer, you can create an account at checkout by adding a password, which saves your address for next time.

Use the order tracking page with the order number from your confirmation email, or with your courier tracking reference. For courier orders, the tracking reference is emailed to you once the parcel is handed to The Courier Guy. For collection orders, the tracking page shows when your order is ready to collect.

Contact us and we will sort it out. Please get in touch before sending anything back, so we can confirm the return address and reference. Your rights under the South African Consumer Protection Act apply in addition to this.

Call 084 306 6660, email [email protected], or use the contact form. You can also come in during opening hours (Mon–Fri 08:00–16:30 · Sat 08:00–13:30 · Sun closed) at Unit 1, 14 John Street, Selby, Johannesburg 2001.

It is sold for motorsport, off-road and diagnostic use. Removing or defeating a working catalytic converter on a road car may affect roadworthy status and emissions compliance in South Africa, and it is the buyer's responsibility to confirm what is legal for their vehicle and how they use it.

This part alters how your vehicle reports downstream oxygen sensor readings. Removing or bypassing a functioning catalytic converter on a road-going vehicle may affect its roadworthy status and emissions compliance in South Africa. Sold for motorsport, off-road and diagnostic use. It is the buyer's responsibility to confirm what is permitted for their vehicle and use case.

No. The spacer changes what the downstream oxygen sensor reports; it does not repair a catalytic converter and it does not reduce what comes out of the tailpipe. If your vehicle has to meet an emissions standard, the answer is a working catalytic converter.

A standard South African roadworthy inspection is largely mechanical and visual, and it does not currently include a tailpipe emissions analysis or an OBD scan on most vehicles. In practice a P0420 on its own is unlikely to be the thing that fails you, but the presence of a permanently lit engine warning lamp on the dash can be flagged by an examiner, and a missing or visibly cut-out catalytic converter is something an inspector can see. Rules and enforcement differ between testing stations and can change, so confirm with your testing station rather than assuming.

Removing or defeating a working catalytic converter on a road car may affect roadworthy status and emissions compliance. The spacer is sold for motorsport, off-road and diagnostic use, and it is your responsibility to confirm what is legal for your vehicle and how you use it.

Removing or defeating a working catalytic converter on a road car may affect roadworthy status and emissions compliance. Nothing that clears the light changes what is coming out of the tailpipe. If the car needs to be compliant, the answer is to refit a catalytic converter.