Plug-in Hybrid Spark Plugs: Heat Range Isn't Spark Energy

Plug-in hybrid spark plugs: heat range isn't ignition energy or material grade

Scope: 2026 Qin L DM-i, China mainland; PDF p. 358 maintenance items; NGK's general heat-range explanation gives no fitment part number for the Qin L

What heat range means

NGK's official basics explain that a spark plug's heat range describes its thermal operating characteristics and bears no relation to the electrical energy passed through the plug. When choosing a plug, "hotter" must not be read as "a stronger spark". Heat range has to balance avoiding fouling against avoiding overheating, and electrode material marketing cannot replace correct thermal matching; this article does not specify a heat range number for the Qin L on that basis. ^{[1] [2]}

Too cold and too hot are different problems

NGK explains that choosing too cold a heat range can cause carbon fouling, while too hot can lead to electrode damage or even pre-ignition. The Qin L maintenance schedule lists spark plug maintenance requirements, but this page gives no replacement part number. So the workshop should check the manufacturer's fitment; starting or acceleration complaints should not be handled by changing the heat range on the basis of material, price or experience with another model. ^{[1] [2]}

Keep diagnosis and replacement within the approved part

NGK also notes that insulator damage, carbon build-up and excessive gaps may be linked to misfires, but these are general causes and cannot pin a symptom on a particular Qin L spark plug. This article gives no gaps, torques, removal steps or heat-range changes; professionals should complete the repair using this car's diagnosis and the approved part number, and owners should not drive at high revs to try to burn off fouling. ^{[1] [2]}

Sources

[Source 1] BYD China official website: 2026 Qin L DM-i Owner's Manual (in Chinese) (public PDF on the official website)
https://www.byd.com/material/domestic-official/user-manual/dynasty/2026%E6%AC%BE%E7%A7%A6L%20DM-i%E7%94%A8%E6%88%B7%E6%89%8B%E5%86%8C20260417.pdf
[Source 2] NGK: Spark Plug Basics
https://ngksparkplugs.com/en/resources/spark-plug-basics
Verified: 2026-10-03; page publication date not confirmed.

This article contains information-organising suggestions from the editorial team; it is not a manufacturer repair procedure.