Frequently asked questions

The MiniCats SA mini catalytic converter O₂ sensor spacer is R199.00. Standard courier delivery is R99 and takes 2 to 4 business days; express is R149 for next business day.

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

No. Guest checkout is available. Payment is handled by PayFast, which accepts cards and instant EFT.

A tracking reference is issued once the parcel is collected by the courier. You can follow it on the order tracking page.

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.

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.

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. On a borderline or ageing catalyst it often works, and on a badly failed or hollowed-out one it frequently does not.

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.

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.

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.

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.

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.

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.

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.

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 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.

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.

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

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.

It usually does, but check before you tighten anything. The spacer moves the sensor 58 mm further out of the bung, so the loom has to take up that 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.

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.

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.

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. Some vehicles also use aggressive monitor strategies that need more offset than a single spacer provides. Diagnose the exhaust and sensor before assuming the spacer is at fault.

No. The spacer is supplied on its own and you reuse your existing downstream sensor. If your sensor is old, contaminated or already throwing its own fault codes, replace it first — a spacer will not compensate for a sensor that has stopped responding properly.

It fits if your downstream oxygen sensor has an M18 × 1.5 thread and there is 58 mm of clear space behind the bung for the spacer to stick out into. That covers the large majority of petrol vehicles. Check your sensor part number or measure the thread on the old sensor to confirm before ordering.

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 takes about five minutes and 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 look at where the sensor tip would end up if it moved out by that distance. 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. Moving the sensor 58 mm further out means the loom must cover that extra distance 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: M18 × 1.5 thread and 58 mm of clearance. Whether it will clear the resulting code is a separate question, and a fully decatted car with no catalyst at all is the hardest case for any spacer to mask. The mini catalyst element in this design gives it a better chance than a plain hollow spacer, but there is no guarantee on a full decat.

No. The spacer is supplied on its own and you reuse your existing downstream sensor. That also means the spacer has to match your current sensor thread, which is the main thing to verify before ordering.

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.

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.

Sometimes, but not reliably. On a badly failed or removed catalyst the downstream sensor sees almost the same gas as the upstream sensor, and a single short spacer may not damp it enough. Cars with aggressive monitor strategies may need a mini-cat type spacer, a longer or double spacer, or an ECU tune instead.

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.

A spacer is a roadside job: unscrew the downstream oxygen sensor, thread the spacer into the bung, thread the sensor into the spacer, clear the code. Budget about fifteen minutes plus penetrating oil soak time. A catalytic converter replacement is a workshop job, usually a few hours, and often involves cutting and welding.

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.

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.

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.

Often, but not always. A spacer with a miniature catalyst element damps and delays the gas the sensor samples, which is usually enough on a mild decat or a high-flow cat. On a full straight pipe, or a vehicle with an aggressive monitor strategy, one short spacer may not be enough and you may need a longer or double spacer, or a tune.

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.

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.

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 R199 and ships from Johannesburg, Gauteng via The Courier Guy.

The MiniCats SA mini catalytic converter spacer is R199. Shipping is R99 for standard delivery or R149 for express. Imported listings can look cheaper before you add international shipping, the exchange rate, and any customs and clearing charges on arrival.

Standard shipping is R99 and takes 2 to 4 business days from Johannesburg to a main centre such as Cape Town, Durban, Gqeberha or Bloemfontein. Express is R149 for next business day delivery. Outlying towns and farm addresses generally add time to whatever the main-centre figure is.

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.

Count your downstream oxygen sensors, not your engine size. A typical inline four has one post-cat sensor and needs one spacer. A V6 or V8 with two banks usually has two, and if you are chasing both P0420 and P0430 you need one for each bank.

It fits any vehicle whose downstream oxygen sensor uses the standard M18 × 1.5 thread, which is the vast majority. Check by unscrewing your existing sensor and measuring the thread, or by looking up the thread specification for that sensor part number. Also check you have room around the bung for a part 58 mm long and 16 mm in diameter.

No. The spacer is the threaded body only. Your existing downstream oxygen sensor unscrews from the exhaust, the spacer goes into the exhaust bung, and the sensor then threads into the spacer. If your sensor is old and seized, budget for the possibility that it does not survive removal.

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 works on cars where a hollow tube alone does not. If a listing does not say, assume it is hollow.

South African stores commonly support card payments, EFT and instant-EFT gateways. Check the checkout page before ordering, and be cautious of any private seller who will only accept a direct bank transfer with no order record and no invoice.