This is a subtler fault than a GHD that won't heat at all — and easy to misread. Your straighteners do warm up, they feel warm to the touch, but they're just not getting properly hot: your hair won't straighten the way it used to, you're going over the same section again and again, and it takes far longer than it should. If that's your situation, the cause is usually different from a total no-heat fault, and it's repairable.
I've been repairing electronics for over 25 years, so here's what "warm but not hot enough" usually means and how it's put right.
First, which fault have you actually got?
It's worth being precise, because "not heating properly" can mean three different things — and each has a different cause:
Warms up, but not hot enough to style — this page. Usually a temperature-sensing or control fault.
Doesn't heat at all, both plates stay cold — a different fault (usually the thermal fuse). See why won't my GHD heat up.
Gets hot, then cools down after a few minutes — different again. See GHD heats up then cools down.
If yours genuinely reaches a warm but underwhelming temperature and stays there, read on.
What causes a GHD to under-heat
A working GHD holds its plates at a specific styling temperature — around 185°C on most models. To do that, the straighteners rely on a temperature sensor (a thermistor) that constantly measures the plate temperature and tells the control electronics when to add more heat and when to ease off.
When a GHD warms up but never reaches full temperature, it's usually because that sensing-and-control loop isn't working correctly. The most common causes are:
A failing temperature sensor (thermistor) — if the sensor misreads the plate temperature, the straighteners can "think" they're hotter than they really are, and stop heating too early. The result: warm plates that never get properly hot.
A partially failing heater element — an element on its way out can still produce some heat, just not enough, giving you weak, under-temperature plates.
A control-board fault — less common, but a problem on the circuit board can throw off how the straighteners regulate their heat.
Because these causes overlap, the only reliable way to know which it is on your specific pair is to open them up and test — which is exactly what the repair involves.
Why it's worth fixing rather than living with
It's tempting to just put up with straighteners that "sort of work" — but under-heating is worth sorting for two reasons. First, going over the same hair repeatedly with lukewarm plates actually risks more heat damage to your hair than one pass with correctly-hot ones, because you're applying heat for far longer. Second, an under-heating fault often gets worse over time as the failing component deteriorates — so what's mildly annoying now can become "won't heat at all" later. Fixing it early is usually the cheaper, easier path.
How the repair works
When an under-heating GHD comes in, I test the temperature sensor, the heater elements and the control side to find the actual cause, replace what's failed, and then — crucially — heat-test the straighteners to confirm both plates reach the correct styling temperature before they come back to you. That last step matters especially with this fault, because "hot enough" is the whole point. Everything is PAT safety-tested too.
It's a flat £29 all-in for standard models (£39 for Gold, Max and Platinum+) — parts, labour, return postage and safety test included — backed by my no-fix-no-fee promise and a 12-month warranty against the same fault returning.
Is it worth repairing?
For a straightener that under-heats, yes — it's almost always a single failing component (a sensor or an element) on an otherwise good pair, and a £29 repair beats replacing them for £100-plus. The exceptions, as ever, are the sealed round-button Eclipse and Platinum (S8T261) models, which can't be repaired internally.
If your GHDs warm up but won't get properly hot, you can book a straightener repair here — I'll send simple instructions for posting them in and confirm the exact cause when they arrive. Not sure which fault yours is? See all the GHD repairs I offer and pick the closest, or send them in and I'll diagnose it for you.
The Repair Works is an independent UK repair service, run by me, Paul — 25 years of hands-on repair experience, working by post for customers across the whole country. Not affiliated with or endorsed by GHD.
