Land Rover Defender Spark Plugs: Intervals, Fitment & Warning Signs
On the Defender, related Land Rover engines genuinely use a wasted spark system, where each coil fires two specific cylinders together.
Illustration for editorial purposes
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OEM Part Number: confirm via engine code — aftermarket NGK 6637 / Bosch 0 242 240 653
| Petrol engines in this generation | See the fitment notes |
|---|---|
| Spark plugs (aftermarket) | NGK 6637 (iridium, 20.8 mm hex, M14x1.25); NGK 4008 (nickel, 20.8 mm hex, M14x1.25); Bosch 0 242 240 653 (0.7 mm, 16 mm hex, M14x1.25); Bosch 0 242 235 663 (0.8 mm, 20.8 mm hex, M14x1.25); Denso IW20TT (iridium, platinum earth); Champion CET2 (0.9 mm, 16 mm hex, M14x1.25); Beru UPT8 (0.9 mm, 21 mm hex, M14x1.25) |
| Genuine (OE) numbers quoted | 7700500048 is quoted against Denso W16EPR-U and 1WT118110 against Denso W16TT; neither is a Land Rover number |
| Fitment notes | the L663 petrol engines (2.0 P300 and 3.0 P400 mild hybrid) are not named in the source. |
Land Rover Defender Spark Plugs: A Cheap Part That Causes Expensive-Feeling Problems
On the Land Rover Defender, symptoms of worn spark plugs are subtle by nature — a touch rougher at idle, a little less responsive off the line — and easy to attribute to almost any other engine gremlin. Because the part itself is so cheap, it's routinely overlooked well past when it should've been changed.
Land Rover Defender Spark Plugs: What They Do
How well the Land Rover Defender's engine runs, how efficiently it burns fuel, and how smooth it feels are all tied to spark plug condition, since these ignite the compressed fuel-air mixture in each cylinder. That's a petrol-engine job specifically — diesels ignite fuel through compression and have no spark plugs at all.
Land Rover Defender Spark Plugs: Generations & Spark Plug Count
| Diesel variants | Not applicable — diesel engines use compression ignition and have no spark plugs at all |
|---|---|
| Petrol variants (all trims) | 4 spark plugs — one per cylinder |
Land Rover Defender Spark Plugs: Watch: Replacing It
L663 P300; P400 alt 69CvjKLdGwI.
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A Genuinely Useful Piece of Context Worth Knowing About Misfires — Land Rover Defender Spark Plugs
If you're facing a misfire, this is genuinely worth knowing: related Land Rover engines have used a wasted spark ignition system, where each coil fires two specific cylinders together, meaning a genuine coil failure should typically produce a misfire matching a specific pair rather than a single, isolated cylinder.
It's also genuinely worth knowing that the official service interval for platinum spark plugs has been described by experienced mechanics as genuinely too long in practice on related models, with a widened gap at high mileage potentially burning out leads and coils.
Land Rover Defender 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 Land Rover Spark Plugs
The same part, covered across other Land Rover models.