Throughout, the counts are fault codes only. Most brands also publish a handful of status displays - defrost, filter reminders, Wi-Fi pairing - and those are excluded here, because a shared "filter is dirty" indicator says nothing about the platform underneath.
What this method proves, and what it does not
Worth being precise, because this is the kind of claim that gets exaggerated online.
Identical fault codes are strong evidence of a shared control platform - the same board, the same firmware family, usually the same OEM building the guts. That is genuinely useful to a buyer, because it tells you which brand's documentation will help you when something goes wrong, and how interchangeable the service knowledge is.
It does not prove corporate ownership, and it does not mean two systems are the same product. Two brands on one platform can differ in coil size, cabinet, compressor sourcing, cold-weather tuning, warranty and support. A shared platform is a family resemblance, not a twin.
The comparison also gets weaker as the tables get shorter. Two brands sharing six codes tells you very little; two brands sharing 36 out of 36 tells you a great deal.
We also checked the obvious alternative and it came up empty, which is worth reporting. Several brands publish identical performance figures at the same capacity - ACiQ Extreme, Blueridge XS5 All Climate Plus and Senville AURA are all SEER2 25.4, HSPF2 10.5 and rated to -22F at 12,000 BTU - but no two brands in our catalog share an AHRI certificate number. Each certifies its own equipment separately. So matching specifications hint at a shared origin without proving it, and we have not treated them as evidence here.
The Midea platform is the biggest family
ACiQ publishes exactly Midea's table: 36 fault codes each, all 36 shared, a perfect match. This is the cleanest result in the whole comparison, and it matches what is already known - ACiQ is a distributor house brand built on Midea hardware. If you own an ACiQ, Midea's documentation is your documentation. We cover it in the ACiQ review.
Carrier's ductless table is the surprise. All 31 fault codes Carrier publishes for its ductless equipment also appear in Midea's 36 - every single one. A major American HVAC name and a value brand, running the same fault-code vocabulary.
Senville shares 23 codes with Midea, about 64% of the smaller table - a real family resemblance rather than a clone. Senville publishes 44 fault codes in total, so it has extended the platform's vocabulary rather than simply copying it.
The practical upshot: if you own an ACiQ, a Carrier ductless system or a Senville, and your brand's documentation is thin on a particular code, the Midea material is worth reading. Start at the error-code library.
Carrier and Toshiba Carrier share nothing
This one deserves its own heading, because the badge actively misleads.
Carrier's ductless codes and Toshiba Carrier's codes overlap by zero. Not "a little" - none of Carrier's 31 fault codes appear among Toshiba Carrier's 49.
They are entirely separate platforms sold under closely related names. If you have a Toshiba Carrier system and you go looking for help using Carrier's ductless documentation, nothing will line up, and you may well conclude your unit is faulty in some undocumented way when it is simply speaking a different language. Use the Toshiba Carrier table, not the Carrier one.
The GREE family: TOSOT and Cosmo
TOSOT publishes 14 fault codes, and 13 of them appear in GREE's 52. Cosmo publishes the same 14, with the same 13 matching.
This is consistent with what the brands themselves say - TOSOT is GREE's sibling brand under the same parent, and Cosmo is sold through TOSOT's direct channel. The code tables simply confirm it. The shorter lists look like curated subsets of GREE's fuller table rather than different systems, with a single code apiece that GREE does not list.
For an owner, that means GREE's documentation is the deeper resource, and a Cosmo or TOSOT fault will almost always be explained there.
The cluster nobody talks about: Pioneer, Klimaire and Della
This is the most interesting finding, because these three are usually discussed as unrelated brands.
- Every one of Klimaire's 51 fault codes appears in Pioneer's 52. A complete match, not a partial one.
- Della and Pioneer share 49 codes.
- Della and Klimaire share 49, out of Della's 59.
Three brands, one code vocabulary, three separate badges and three separate reputations. If you are cross-shopping Pioneer against Klimaire against Della and treating them as genuinely different engineering choices, the fault codes suggest you are largely choosing between distribution, warranty and support rather than between platforms.
And those differ a lot. Pioneer's warranty runs 5 years on the Diamante lines and up to 10 on the Quantum lines; Klimaire's base coverage is only 3 years parts unless you register within 45 days. Same platform, very different ownership experience - which is exactly why our warranty comparison is worth reading alongside this.
Notably, Pioneer shares not a single code with Midea. It is its own family, not part of the big one.
Brands that stand genuinely apart
The separations are as informative as the matches. Against Midea's 36 fault codes:
- Mitsubishi Electric (59 codes) shares none.
- Daikin (54 codes) shares none.
- LG (36 codes) shares none.
Not one code in common across three of the largest tables we hold - which is about as clean a separation as this method can produce.
These are independent platforms with their own engineering lineage, which is part of what you pay for with the majors. It also means their documentation is not interchangeable with anything else - and that their dealer networks and parts channels are genuinely their own.
Where our data is too thin to say
Two results look suggestive but do not clear the bar, and we would rather say so than round them up.
Blueridge and Cooper & Hunter publish 6 fault codes each and share all 6. A perfect match on a six-item list is not much of a match: those six are the common failures every brand documents, and any two tables that short would likely align by coincidence. This one proves nothing on its own.
Haier and GE Appliances share all 3 of Haier's codes, which sounds conclusive until you notice Haier's table has just 3 entries. It is worth mentioning only because a second, independent signal points the same way: GE's Endure line and Haier's Arctic Series appear to be the same hardware family above 12,000 BTU. Two weak signals agreeing is a hint, not a finding.
Why this matters when you are buying
Three practical takeaways.
Service knowledge follows the platform, not the badge. If your brand's documentation is thin, its platform siblings may cover the same code properly. That is a real advantage of buying into a large family like Midea's or GREE's.
A "different brand" may not be a different bet. Cross-shopping Pioneer, Klimaire and Della gets you three warranties and three support experiences, but broadly one platform. Diversifying across those three is not the risk hedge it looks like.
Judge on the things that actually differ. Since the platform is often shared, the decisions that remain are warranty terms, registration deadlines, cold-weather rating, efficiency and who answers the phone. Those vary enormously between brands that are otherwise siblings.
Look up your own system's codes in the error-code library, or compare specs across brands in the product finder.