Most used-genset listings tell you the rating, the make and the hours. None of them tell you whether the machine can lawfully run at your site — and that is the question that decides whether a cheap set is a bargain or a stranded asset. Two facts settle it: the year the engine was manufactured, and the state it is going to run in.
TL;DR
- CPCB IV+ is a purchasing rule for new sets, not a retrofit order. Buying a used CPCB II set is not illegal, and no retrofit turns one into a CPCB IV+ set
- One vintage is an absolute stop: engines made and installed before 1 July 2004 are to be scrapped — not sold, not re-sited, not run
- Where it lands matters more than where it came from. Maharashtra, Karnataka and Delhi-NCR each impose obligations that most of India does not
- Consents do not travel with the machine. Re-siting a used set is a new installation in the eyes of your state board
- The regime detail, with the gazette references, lives in CPCB II vs CPCB IV+ vs RECD — this page is the buyer’s decision path through it
The one answer that is always no
If the engine was manufactured and installed before 1 July 2004, CPCB’s RECD procedure is unambiguous: such engines are to be scrapped — not sold, not used, not run. No retrofit rescues them, and no price makes them a good idea.
This matters commercially, not just legally. A set of that vintage is often the cheapest thing on offer, and the reason it is cheap is that its only lawful destination is a scrapyard. The liability travels with the machine to whoever owns it next. We will not buy one and we will not sell one, and any dealer who offers you one either does not know the rule or is hoping you do not.
Question one: how old is the engine?
Not the invoice. Not the year it was commissioned. The year stamped on the engine nameplate, because that is what fixes the emission stage the machine was certified to, and that stage travels with it for life.
| Engine manufactured | Emission stage it can hold | What that means when you buy it |
|---|---|---|
| Before 1 July 2004 | None notified | Stop. Scrapping is the only lawful route |
| 1 July 2004 – 30 June 2014 | Pre-CPCB II stages | Legal to own; the likeliest candidate for a retrofit obligation, and the hardest to place |
| 1 July 2014 – 30 June 2023 | CPCB II (G.S.R. 771(E)) | The bulk of the used market. Legal to buy and re-site, subject to the destination rules below |
| From 1 July 2023 | CPCB IV+ (G.S.R. 804(E)) | Barely any exist second-hand yet, and they command a premium when they do |
A note that saves arguments: a CPCB II set delivered in early 2024 can be entirely legal, because the transition clauses let manufacturers build to the earlier norms into December 2023. If you are looking at a set from that window, ask for the purchase-order date, not just the invoice — the point is made in more detail in CPCB IV+ norms, explained.
Question two: where is it going to run?
This is the half that buyers routinely skip, and it is the half that bites. The same used set faces three different worlds:
- Delhi-NCR — effectively closed to a plain-diesel used set. CAQM Direction No. 76 requires dual-fuel conversion and/or a CPCB-certified RECD by capacity band, GRAP escalations ban usage outright on bad-air days, and CAQM has been sealing violators. Buying a used diesel set into NCR is the single most expensive mistake available in this market.
- Maharashtra — the MPCB circular of 2 June 2023 brought qualifying in-use sets into an RECD requirement state-wide. That compliance window closed on 31 December 2023 and the obligation is now enforced through consent conditions. If you are buying into Pune, Mumbai or anywhere else in the state, price the retrofit in before you agree a number, not after.
- Karnataka — the KSPCB notification of 25 May 2023 makes an RECD mandatory at 125 kVA and above. Below that, obligations live in your consent conditions.
- Everywhere else — as at the review date on this page, no blanket national retrofit mandate exists. What binds you is your own consent to operate, which is a site-specific document and not a general rule.
An RECD is not a CPCB IV+ certificate
Worth stating flatly, because it is the most common piece of mis-selling in the used market. A Retrofit Emission Control Device is an exhaust bolt-on for an existing set, certified to capture at least 70% of particulates. It can bring an older set into line with a regional retrofit requirement. It does not change the stage the engine was certified to when it was built, and it cannot make a CPCB II machine into a CPCB IV+ machine. If a listing describes a used set as “CPCB IV+ compliant” and the engine predates July 2023, the claim is wrong.
Consents do not come with the machine
Re-siting a set is a new installation at the destination. The previous owner’s consent to establish and consent to operate covered their premises, their stack height, their acoustic arrangement and their load — none of which transfer. Practically, that means the buyer is responsible for:
- Fresh consent to establish and consent to operate from the state board for the new site
- Stack height computed for the new building, not the old one — our stack height calculator applies the CPCB formula
- Acoustic treatment meeting the enclosure and insertion-loss conditions your board attaches
- Electrical Inspectorate approval for the new installation
- Any RECD obligation that applies at the destination, which may not have applied at the origin
What to get from the seller before you pay
- Photograph of the engine nameplate — the manufacture year and engine serial, legible
- Photograph of the hour meter, and the service log it should reconcile to
- The original invoice or purchase order, especially for anything from the 2023–24 transition window
- The RECD certificate, if one is fitted — the device is certified, so there is paperwork
- The current consent to operate, which tells you what the set was actually permitted to do
- Written confirmation of the emission stage the engine was certified to at manufacture
If a seller cannot produce the first two, treat everything else they tell you as unverified.
Where we stand on this
We buy and sell used sets, so we have an obvious interest in these deals happening. That is exactly why the rules above are stated as limits rather than hurdles: the deals that go wrong in this market are the ones where nobody asked which state the machine was going to, and the cost lands on the buyer months later. Before we sell a used set we check its vintage and its destination against these rules, and where the answer is that it cannot lawfully run at your site, we say so.
This page is a decision path, not legal advice, and state positions move. It carries the review date at the top for that reason. Settle anything marginal against your own consent conditions and your state board before you commit — or ask us and we will check it with you.