Parts for your 2018 Holden Colorado-Ignition coils

2018 Holden Colorado ignition coils — are they even a thing?

Short answer: no. For Australia and New Zealand–delivered 2018 Holden Colorado models (RG series), ignition coils aren’t fitted or required. The Colorado runs the 2.8‑litre Duramax (GM RPO: LWN) turbo‑diesel, a compression‑ignition engine that doesn’t use spark plugs or ignition coils. Technical sources back this up: GM Holden RG Colorado Service Information for the LWN engine (2017–2019), the 2018 Colorado Owner’s Manual (which references a glow‑plug indicator and no spark‑ignition components), and standard diesel texts such as Bosch Diesel Engine Management all describe diesel systems using high‑pressure common‑rail injection and glow plugs, not coils.

Why no coils? Petrol engines need a high‑voltage spark to ignite the air‑fuel mix, that’s the ignition coil’s job. A diesel like the Colorado’s compresses air so hot that injected fuel self‑ignites. For cold starts, it uses glow plugs to pre‑heat the combustion chamber, then relies on precise fuel metering by the ECU and high‑pressure injectors. So there’s simply nothing for an ignition coil to do.

What should owners look after instead of coils? Think diesel essentials. Keep to the logbook schedule for fuel filter changes, use quality diesel, and drain any water traps if equipped. If starting gets sluggish or the engine runs rough under load, common culprits are tired glow plugs, restricted fuel filters, injector spray pattern issues, or intake/EGR carbon build‑up rather than a failed “coil”.

• No‑start or hard‑start when cold: have the glow plugs and glow control circuit checked.
• Rough running or “misfire” feel: scan for injector balance rates, check rail pressure, and inspect the fuel filter and air intake for restriction.
• Warning lights or limp mode: read DTCs before replacing parts, diesel faults are often fuel‑system or boost‑control related.

Note: in some overseas markets, other Colorado variants (like petrol V6) do use coil‑on‑plug systems. But for Aussie and Kiwi 2018 Holden Colorado models, an ignition coil isn’t fitted and isn’t a service item.

Technical references: GM Holden RG Colorado Service Manual (Engine: 2.8L Duramax LWN, 2017–2019), Holden Colorado Owner’s Manual (2018), Bosch Diesel Engine Management (common‑rail compression‑ignition principles). These confirm no spark‑ignition hardware — and therefore no ignition coils — on the 2018 Colorado diesel.

Popular questions about 2018 Holden Colorado ignition coils

Does a 2018 Holden Colorado have ignition coils?
No. The 2018 Colorado in Australia and New Zealand is a 2.8‑litre turbo‑diesel that uses compression ignition and glow plugs, not spark plugs or coils. If someone’s selling “ignition coils” for it, they’re likely listing generic parts not applicable to the diesel model.

Why does my Colorado feel like it’s misfiring if there are no coils?
A diesel can feel “misfire‑y” from fuel system or air issues: a clogged fuel filter, injector imbalance, low rail pressure, intake leaks, or EGR/soot build‑up. Get it scanned for fault codes, check injector balance rates, and follow the logbook service items first.

Can I retrofit ignition coils or spark plugs to improve performance?
No. Converting a diesel to spark ignition isn’t practical — it would require a different engine. For smoother running or more go, focus on clean filters, quality fuel, correct tyre pressures, and reputable ECU calibrations where legal.