Peugeot 308 Spark Plugs: Intervals, Fitment & Warning Signs

On the 308, a genuine, real phenomenon on the 1.2 PureTech engine explains knocking under load — plus real, documented plug part number confusion worth checking.

Illustration for editorial purposes

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Peugeot 308 Spark Plugs: OEM Part Number

Accuracy note: we weren't able to verify a confident Peugeot 308 spark plugs part number at the time of writing. Please confirm the correct part via a Peugeot dealer or parts specialist using your VIN.

A Genuine, Real Phenomenon Worth Understanding: LSPI on Turbo PureTech Engines — Peugeot 308 Spark Plugs

If your car has a PureTech turbocharged petrol engine and you're experiencing a knocking or misfiring sensation specifically under load at low engine speed, it's worth knowing about Low Speed Pre-Ignition (LSPI) — a genuine, industry-recognised phenomenon affecting small, turbocharged direct-injection engines generally, not something unique to Peugeot. It occurs when the fuel-air mixture ignites prematurely, before the spark plug fires, causing a knock that can potentially damage the engine over time if it happens repeatedly. Genuinely useful to know: LSPI is understood to be exacerbated by certain oil additive packages, and switching to an oil that meets the correct, current specification for this engine — combined with using a higher-octane fuel, which some owners report noticeably reduces the frequency of the knock — are the cheapest, simplest first steps worth trying.

A genuinely confusing, real fitment detail worth checking carefully: there's documented confusion among both parts suppliers and owners about the correct spark plug for this engine — some sources list the ZR5 heat range as the current Bosch-recommended part, while many retailers still show the ZR6 as standard, with owners speculating Bosch may have revised their recommendation at some point without this being consistently reflected across every parts catalogue. Given how sensitive these small turbo engines can be to using the wrong heat-range plug, it's genuinely worth cross-checking your specific engine code against your VIN via a specialist parts lookup rather than assuming the first result from a generic search is correct.

Peugeot 308 Spark Plugs: A Cheap Part That Causes Expensive-Feeling Problems

On the Peugeot 308, there's rarely a clear signal when spark plugs wear out — just a rougher idle, marginally less pep off the line — vague enough to get pinned on other engine issues. Since the part costs so little, it's also one of the easiest things to keep putting off.

Before you buy: plug type and gap specification vary by engine size and generation. Always confirm against your VIN before ordering.

Peugeot 308 Spark Plugs: What They Do

On the Peugeot 308, combustion efficiency, fuel economy and smooth running all trace back to spark plug condition, since these are what ignite the compressed fuel-air mixture in each cylinder. Petrol engines depend on them entirely — diesels skip spark plugs altogether, igniting fuel through compression instead.

Peugeot 308 Spark Plugs: Generations, Engines & Spark Plug Count

Diesel variants (BlueHDi)	Not applicable — diesel engines use compression ignition and have no spark plugs at all
1.2 PureTech/THP (standard petrol trims)	Genuinely only 3 spark plugs — this engine is shared across the wider PSA/Stellantis range (Peugeot, Citroen, DS), not a four-cylinder
GTI/GT (1.6 THP, where fitted)	4 spark plugs — the performance derivative uses a genuinely different, larger four-cylinder engine from the standard car's 3-cylinder unit

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Peugeot 308 Spark Plugs: Warning Signs, DIY Difficulty & Aftermarket Advice

These are the same regardless of make or model — see our full Spark Plugs Guide for symptoms of worn plugs, why matching your exact plug specification matters, and trusted brands to buy from.

More Peugeot Spark Plugs

The same part, covered across other Peugeot models.