Your diesel heater won't light on a cold morning? Nine times out of ten, the glow plug is the part that quit. It pumps fuel, runs the fan, then throws an ignition error.
This is a silicon nitride glow plug made in Japan, in 12V or 24V. At its rated voltage it reaches 2,012°F (1,100°C) or more within 60 seconds, so your heater lights on the first try.
Every number on this page comes from the manufacturer's drawing. You can check the heat-up spec, the resistance and the thread against your old plug before you order.
| Spec | Detail |
|---|---|
| Material | Silicon nitride (Si₃N₄) ceramic glow pin, made in Japan |
| Voltage | 12V or 24V |
| Heat-up | 2,012°F (1,100°C) or more within 60 seconds at rated voltage |
| Power | 70W or more |
| Resistance at 68°F (20°C) | 12V: 0.4–0.6 Ω · 24V: 1.3–2.2 Ω |
| Thread | M10 × 1 |
| Ceramic tip | 0.18 × 1.76 inch (4.5 × 44.7mm) |
| Lead wires | PFA-insulated · green + yellow = 12V · blue + yellow = 24V |
| Thermal expansion | 3.7 × 10⁻⁶/°C (silicon nitride) |
| Vickers hardness | 17.1 GPa (silicon nitride) |
| In the box | Pre-wired plug, rubber seal and connector |
| Fits | Espar / Eberspächer Airtronic D2, D4, D4S · Chinese 2KW–8KW heaters · Webasto — compare first |
Why a Silicon Nitride Pin Lasts Longer
A silicon nitride pin lasts because it barely expands when it heats. Its thermal expansion rate is 3.7 × 10⁻⁶/°C, so it doesn't micro-crack through thousands of heat-and-cool cycles.
The material is also hard — 17.1 GPa on the Vickers scale. The tip resists erosion from the fuel spray, so the glow surface stays intact instead of pitting and losing output.
Fast heat-up matters most on cold mornings. This pin reaches 2,012°F (1,100°C) within 60 seconds at rated voltage, so your heater doesn't crank through failed cycles that drain the battery.
The leads are PFA-insulated, a fluoropolymer that handles heat without melting or going brittle. That keeps the connection solid at the point where many replacement plugs fail first.
What It Fits — Webasto, Espar & Chinese Diesel Heaters
This glow plug fits Chinese 2KW, 5KW and 8KW diesel heaters directly. It also fits Espar / Eberspächer Airtronic D2, D4 and D4S heaters, part number 252069011300.
For Webasto and Thermo King heaters, hold it next to your old pin first. If the thread and tip size match, it's the pin your heater takes.
Three checks confirm the fit in two minutes:
- M10 × 1 thread on the plug body
- Ceramic tip about 0.18 inch (4.5mm) across and 1.76 inches (44.7mm) long
- Resistance in the right range for your voltage (see below)
It ships pre-wired with a rubber seal and connector, so most replacements are plug-and-play. If your heater uses a different connector, splice the two leads onto your existing wires.
12V or 24V — How to Choose the Right One
Match the glow plug to your heater's voltage, not your battery bank. Pick 12V for most vans, RVs, campers, cars and boats. Pick 24V for trucks, buses and heavy equipment.
The pin is voltage-specific. Put a 12V plug on a 24V system and it burns out in minutes. Put a 24V plug on 12V and it never gets hot enough to light your fuel.
Not sure which you have? Put a multimeter across your old plug at room temperature. A 12V pin reads 0.4–0.6 Ω and a 24V pin reads 1.3–2.2 Ω — the two ranges don't overlap.
The wire colors tell you too. Green and yellow leads mean 12V; blue and yellow mean 24V.
How to Tell Your Glow Plug Has Failed
A failing glow plug shows one clear sign: your heater pumps fuel and runs the fan, but never lights. You hear the pump ticking, smell raw diesel, then the unit throws an ignition error and shuts down.
Watch for these symptoms:
- Repeated failed start cycles, then a lockout or error code
- White smoke and an unburnt-fuel smell at the exhaust
- Hard starting that takes several tries in the cold
- Lights fine when warm, but not on freezing mornings
Two quick checks confirm it. Look at the tip: a cracked, blistered or heavily sooted surface is finished. Then measure resistance — an open circuit means the element has burned through.
Replace it before failed cycles drain your battery or flood the burner. A fresh pin brings most heaters back to a clean first-cycle start.
Frequently Asked Questions
How long does a diesel heater glow plug last?
With regular winter use, plan on replacing it every two to three years. Carbon buildup is what kills glow plugs early. Run your heater on high for five to ten minutes before you shut it down, and the residue burns off.
Why does this cost more than the $15 glow plug kits?
You get a pin with published numbers: 2,012°F (1,100°C) within 60 seconds, a tested resistance range and an M10 × 1 thread. You can check all three before you fit it. It also arrives pre-wired with the seal and connector, ready to install.
Do I need a special tool to replace the glow plug?
No special tool — a standard socket or spanner removes and refits it. Never use pliers or over-tighten it, because the silicon nitride tip can crack under too much force. Snug it firmly by hand, no more.
Will it fit my Webasto or Espar heater?
It fits Espar / Eberspächer Airtronic D2, D4 and D4S heaters, part number 252069011300, and almost all Chinese 2KW–8KW heaters. For Webasto, hold it next to your old pin first and check the thread and tip size. Always match the voltage, 12V or 24V.
Is silicon nitride the same as a ceramic glow plug?
Silicon nitride is a ceramic, and one of the toughest for this job. What matters is how the pin handles heat: this one expands only 3.7 × 10⁻⁶/°C and reaches 2,012°F (1,100°C) within 60 seconds. That resistance to thermal shock is why it lasts.
Does it come with a seal, or do I reuse my old one?
Every plug ships with a matched rubber seal, so you don't reuse the old one. Push the rubber boot fully onto the terminal end — it keeps that end below 572°F (300°C). Fit the seal dry and don't over-tighten.
Buy It With Confidence
Every plug is backed by our quality guarantee. If it arrives defective or fails from a manufacturing fault, we replace it, no hassle. You're buying direct from Vvkb, a diesel heater manufacturer since 1996, not a reseller.
Order the silicon nitride glow plug in 12V or 24V, with the seal and connector ready to install.
