Fitted an aftermarket CNG kit? Owners report warranty refusals and RCs with no endorsement: what the rules say

A CNG kit is still the cheapest way to cut a running cost in India, and it is also the modification that most often ends in an argument at the service desk. The pattern owners describe is consistent: the kit works, the savings are real, and then a clutch, an injector or a wiring harness fails and the dealer points at the kit.

Team-BHP's Modifications and Accessories section would not open for me, so I am going by what search results show. Search results show at least five separate Team-BHP threads on retrofit CNG, including a long-running "Advice on CNG Conversion" thread that runs to at least page 49, a thread on aftermarket kit experience and filter changes, and threads on fitting CNG to automatics and to the Maruti Wagon R, plus two owner reviews on the site, one on an Ignis with a retrofit kit and one on a Magnite owner's experience with Nissan's own kit. In those results owners report engine and wiring warranty being treated as void after an aftermarket fitment, difficulty getting CNG endorsed on the RC, and the risk of a claim being refused. I did not open those pages, so I am not giving post counts, dates or quotes from them. On the mycarhelpline owner board, which did open, a question from January 2013 about a six month old Hyundai i10 drew the flat answer that going for the kit will void the warranty, and a 2014 question about a kit fitted in 2010 and never entered in the RC drew the reply that the insurance would be treated as null and void if a claim arose.

What the law actually requires

Section 52 of the Motor Vehicles Act says that where an owner modifies the engine or any part of it to run on another fuel or energy source, including compressed natural gas, by fitting a conversion kit, that modification "shall be carried out subject to such conditions as may be prescribed", and that the Central Government may prescribe specifications and conditions for approval and retrofitment of such kits. Sub-section (3) says that where an alteration has been made without the approval of the registering authority, the owner shall report it to the registering authority within fourteen days.

The approval route exists. The Ministry of Road Transport and Highways notified retrofitment of CNG and LPG kits on BS-VI petrol vehicles, and replacement of diesel engines with CNG or LPG engines, for vehicles under 3.5 tonnes, with type approval requirements laid down. So a BS6 car can legally be converted, but only with a type approved kit and an endorsement.

The maker-approved option, and the insurer

Several makers now sell dealer-fitted kits that Autocar India, in a 6 May 2026 feature, lists as approved by both the automaker and the RTO. The Kia Carens kit is ₹77,900, Renault's Kwid, Triber and Kiger kits ₹85,000, the Citroen C3 and Aircross ₹98,000, and the Honda Amaze and Elevate ₹1,00,000, with kit warranties of 3 years or 1,00,000 km on most and 3 years or 1,20,000 km on the Hondas. Where a maker has no approved retrofit route for your model, I could not find any public maker statement on warranty, and I am not assuming one.

HDFC ERGO states plainly that a CNG kit must be endorsed in both the registration certificate and the insurance policy, that a comprehensive policy will need extra premium for it, and that both third party and comprehensive claims are affected if the kit is fitted but not endorsed, because the installation is a material change the insurer must know about.

What an owner should do now

Ask the dealer first whether an approved retrofit kit exists for your model and what its warranty covers. Insist on the kit's type approval certificate and the fitment invoice, because the RTO endorsement application needs them. Apply for the fuel change endorsement and tell your insurer in writing the same week, then check the policy copy says CNG. Maharashtra Natural Gas states that a CNG cylinder should be hydro tested every three years, so keep that certificate with the car. If warranty is refused wholesale rather than on the affected part, escalate in writing to the maker's customer care, then the National Consumer Helpline on 1915, and keep the job cards.

Have you had a retrofit kit endorsed without trouble, or a claim questioned because of one? Tell the club what your RTO and your insurer asked for.

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