Diesel Heater Glow Plug (Glow Pin) for 12V and 24V Heaters

The glow plug is the part that lights a diesel air heater, and it is the part you will replace first. Everything else in the burner sits still. The glow pin runs a full heat cycle every time the heater starts. That is why it wears out before the fuel pump, the blower or the control board.

Vvkb fits a silicon nitride ceramic glow pin made by Kyocera in Japan. It is the same class of ceramic pin used in Webasto and Eberspacher air heaters, and it is not the wire-wound metal plug that ships inside budget units. This page covers what the part is, what it fits, how to test it, and how to change it without cracking the ceramic.

The part goes by several names. Glow plug, glow pin, glowpin and ignition plug all mean the same component, and heater listings use them interchangeably. Fitting one in place of a worn wire-wound plug counts as an upgrade, not just a repair.

If your heater will not light, start with the test procedure further down before you buy anything. About half the no-start faults on these heaters are the glow plug screen, not the plug.

What a diesel heater glow plug does, and why ceramic beats metal

The glow pin heats a stainless mesh screen soaked in diesel until the fuel vapour ignites, then the flame becomes self-sustaining and the pin switches off. It works for roughly the first minute of every start cycle. On a heater that runs all winter, that is several hundred heat cycles a season.

Two glow plug types exist in this market. Cheap heaters use a wire-wound metal pin: a resistance coil in a metal sheath. Premium heaters use a silicon nitride ceramic pin, where the heating element is buried inside a solid ceramic body.

The difference shows up in three places you can measure.

Diesel heater glow plug specifications, 12V and 24V

The 12V and the 24V pin are different parts, and the giveaway is the lead colour: green and yellow is 12V, blue and yellow is 24V. They share the same body, the same M10 x 1 thread and the same ceramic. What differs is the element resistance, and that decides everything.

The numbers below come off the Kyocera build drawings for the pins we fit, not off a marketplace listing.

What this glow pin fits: Vvkb, Webasto, Eberspacher and Chinese diesel heaters

The 2KW to 8KW diesel air heater category copied one mechanical interface, so a glow pin for a Chinese diesel heater, a Vevor unit and a Webasto-style clone is normally the same part. The plug threads into the burner head, the screen sits over the ceramic tip, and the two-wire connector goes back to the control board.

Three numbers decide fitment, and you can check all three with a caliper and a multimeter:

• Thread: M10 x 1. The sealing body measures 13.4 mm (0.53 in) across
• Ceramic: 4.5 mm diameter, 44.7 mm long (0.18 x 1.76 in) from the shoulder
• Resistance: 0.4–0.6 ohm for 12V, 1.3–2.2 ohm for 24V. Measure the old pin if it still reads

If those three match, the pin fits. The connector body is the only remaining variable, and it unclips.

Symptoms of a failing glow plug: E09, E11 and what comes first

On a Vvkb heater, error codes E09 and E11 both mean glow plug failure. But the codes are the end of the story. The heater usually tells you something is wrong for a week or two before it locks out.

In order of how they usually appear:

• Longer starts. The heater takes two or three attempts to catch where it used to light first time.
• White smoke that hangs around. A little white smoke at start-up is normal. Smoke that keeps coming for minutes means fuel is going in and not burning.
• A start, then a shutdown. The flame lights, the pin drops out, and the flame dies before combustion is self-sustaining.
• E19, failed to start. On an older heater, this often points at the glow pin or the fuel pump rather than at a fresh air lock.
• E09 or E11. The controller has measured the pin circuit and found it open or shorted. The pin is finished.

Codes are brand-specific. An Eberspacher throws different numbers for the same fault, and so does a no-name unit. The full Vvkb list is on the diesel heater fault code page.

How to test a diesel heater glow plug with a multimeter

A 12V pin should read 0.4–0.6 ohm cold and a 24V pin 1.3–2.2 ohm, both measured at 20°C (68°F). Those are build-spec numbers, not rules of thumb. The test takes two minutes, but the first step is the one people skip.

1. Zero your meter. Set it to the lowest ohms range and touch the two probes together. A cheap meter reads 0.2–0.5 ohm on its own leads. Write that number down and subtract it from every reading.
2. Let the heater cool and cut the power. Test cold. The spec is quoted at 20°C (68°F), so a pin measured in a freezing van reads slightly low.
3. Unplug the glow pin connector at the control board and measure across the two pins on the glow plug side.
4. Read the result against your voltage. 12V: 0.4–0.6 ohm. 24V: 1.3–2.2 ohm. OL or infinity means the element is open, so replace it. A reading near zero is a short.
5. A 12V number on a 24V heater means the wrong pin is fitted. The ranges do not overlap, so this test also catches a bad previous repair.
6. Current check, if you have a clamp meter. Clamp the glow pin feed on DC current and start the heater. The pin draws 70 W or more during pre-glow — about 7.8 A on a 12V unit, about 3.9 A on a 24V unit. No current at all means the fault is upstream, in the controller or the wiring.

One thing that catches people out: measuring at the connector during pre-glow will not show battery voltage. The controller drives the pin by pulse width, and the pin is built for 9.0 VDC on 12V systems and 18.0 VDC on 24V systems. Anything between 10–16 V (or 20–30 V on 24V) at the supply is within its designed range.

The glow plug screen blocks before the plug fails

The stainless mesh screen around the ceramic tip is a consumable, and on most no-start faults it is the actual culprit. The screen wicks diesel and holds it against the hot pin. When it fills with carbon it stops wicking, and the pin ends up glowing in dry air.

Screens carbon up faster if you run the heater long hours on the lowest setting. Low power means a cool, incomplete burn. A weekly run at full output for 20–30 minutes burns the deposits back off.

Two rules that save you a second teardown:

• Replace the screen every time you pull the plug. It costs a fraction of the pin and needs exactly the same job to reach.
• Buy screens in a multi-pack. The Eberspacher reference is 252069100102, and the same screen fits most clone burners.

Glow plug removal and replacement without cracking the ceramic

Ceramic pins break from side load, not from heat, so the removal tool matters more than the torque wrench. A generic deep socket sits on the hex badly and levers the pin sideways. That is how most broken pins get broken.

1. Cool it down and disconnect power. The burner head stays hot long after the fan stops.
2. Blow out the area with compressed air so grit does not fall into the burner when the plug comes out.
3. Unplug the connector, then back the pin out with the dedicated glow plug removal tool or spanner. Keep the tool square to the pin.
4. Pull the old screen. If it is carbon-welded in place, thread a small lag screw into the mesh and pull it straight out with pliers.
5. Inspect the burner bore and clear loose carbon before anything goes back in.
6. Fit the new screen, seated square, then start the new pin by hand for the first few threads.
7. Snug it, do not torque it. Firm by hand plus a light nip is enough. Over-tightening cracks the ceramic and it will not show until it fails.
8. Test before you close it up. Measure the resistance again with the pin installed, then run one start cycle and watch the exhaust.

Full teardown context is in the diesel heater installation guide, and the surrounding components are listed on the diesel heater parts page.

How long a glow plug lasts, and what kills it early

Expect 2–3 seasons of normal use from a ceramic glow pin, and considerably less from a wire-wound one. Life is counted in start cycles, not in running hours. A heater that cycles on and off all night ages its pin faster than one that runs steady.

Four things shorten that life, and three of them are free to avoid.

Altitude also matters. A Vvkb control unit adjusts the air-fuel ratio automatically up to 11,483 ft (3,500 m), so combustion stays clean and the pin stays clean. Heaters without that adjustment soot up fast in the mountains — the detail is in the high altitude guide.

Why Vvkb ships a Kyocera pin instead of a generic one

A glow plug is about 3% of what a diesel heater costs to build and close to 100% of whether it starts. That is the whole argument. Vvkb has been building diesel heaters in China since 1996, and the Kyocera pin is the part we refuse to substitute.

What you get from the factory rather than a marketplace listing:

• The same pin that goes into production heaters, not a lookalike sourced against a photo
• Numbers off the build drawing. We publish the resistance band, the rated voltage, the thread and the ceramic length because we hold the Kyocera drawing. A reseller quotes what the box says
• 12V and 24V both stocked, pre-wired with connector, grommet and seal
• Packaging built for ceramic. A cracked tip is the most common complaint on marketplace glow pins, and it happens in transit
• 10, 50 and 100 packs for fleets, installers and resellers, priced per piece
• Fitment confirmed before you order — send a photo, get a straight answer

The pins in Vvkb heaters are the same ones we sell here. You can see how the rest of the burner is built on the diesel heaters pages, and the certificate numbers for the heaters themselves are listed on the certifications page.

Diesel heater glow plug FAQ

How do you tell if a diesel heater glow plug is bad?

Measure it. A good pin reads 0.4–0.6 ohm on 12V or 1.3–2.2 ohm on 24V once you subtract your meter's lead resistance, and a dead one reads OL. Before it fails outright you will see longer starts, persistent white smoke, and a flame that lights then dies. On a Vvkb heater the controller finally reports E09 or E11.

How long does a glow plug last on a diesel heater?

Two to three seasons of normal use for a ceramic pin. Life depends on start cycles, not hours. Shutting the heater off at the switch instead of the control panel is the single fastest way to halve it, because the cool-down purge never runs and unburnt fuel cokes onto the pin.

Are all diesel heater glow plugs the same?

No. The mounting interface is close to standard across 2KW to 8KW air heaters, but the element is not. A wire-wound metal pin and a Kyocera silicon nitride ceramic pin fit the same hole and behave completely differently at temperature. Voltage differs too, and the resistance gives it away: 0.4–0.6 ohm for 12V, 1.3–2.2 ohm for 24V.

How do you clean a diesel heater glow plug?

Wipe the ceramic tip with a fine abrasive pad, and replace the screen rather than cleaning it. The ceramic is hard enough to take light cleaning without damage. The mesh screen is not worth saving — it costs very little and clogs from the inside where you cannot reach. Never soak the electrical end or bend the pin sideways.

What resistance should a diesel heater glow plug read?

0.4–0.6 ohm on a 12V pin and 1.3–2.2 ohm on a 24V pin, measured cold at 20°C (68°F). Those are the build-spec ranges for the Kyocera pin, and they do not overlap. Cheap multimeters add 0.2–0.5 ohm of their own lead resistance, which is why an untested meter makes a good 12V pin look marginal. Touch the probes together first and subtract that number.

Does a diesel heater have a spark plug?

No. There is no spark and no ignition coil. A diesel heater lights its fuel with a glow plug — a ceramic pin that heats up and vaporises diesel held in a mesh screen. People search for a diesel heater spark plug and land on this part, which is the right one.

Is a heater glow plug the same as an engine glow plug?

No, and they are not interchangeable. An engine glow plug preheats a combustion chamber against compression pressure, with a different thread, length and current draw. A heater glow pin ignites an atomised fuel spray at atmospheric pressure. Fitting one in place of the other does not work.

Will this glow plug fit a Vevor or other Chinese diesel heater?

In most cases yes. The Vevor diesel heater glow plug and this pin share the burner interface used across the 2KW, 5KW and 8KW clone family. Match the voltage — 12V or 24V — and compare the connector to the old one. If either differs, send a photo before ordering.

Will this glow pin fit a Thermo King heater?

Yes, on Thermo King units that use the same M10 x 1 ceramic ignitor. Check three things against your old pin: the M10 x 1 thread, the 4.5 mm by 44.7 mm ceramic, and the resistance. If it reads 0.4–0.6 ohm you need the 12V pin, and 1.3–2.2 ohm means the 24V pin. Send us the unit model if you want it confirmed before you order.

What is Espar part 252069011300, and is your pin the same thing?

252069011300 is the Eberspacher Airtronic D2 and D4 glow pin in 12V. Our pin does the same job in the same fitting, and the matching screen kit is 252069100102. It is a cross-reference, not a genuine Eberspacher part, so confirm your heater model with us if the unit is under warranty.

Do I need the removal tool, or will a normal socket work?

Use the dedicated glow plug removal tool. A generic deep socket seats badly on the hex and side-loads the ceramic, which is exactly how these pins break. If you only have a socket, keep it dead square to the pin and never lever against it.

Do I need to replace the glow plug screen at the same time?

Yes, every time. The screen is a consumable that clogs with carbon, and reaching it takes the identical teardown as changing the pin. Fitting a new pin behind a blocked screen reproduces the original no-start fault within days.

Can I fit a 12V glow plug in a 24V heater?

No. A 12V pin is 0.4–0.6 ohm and a 24V pin is 1.3–2.2 ohm, so the 12V part on a 24V supply draws roughly four times its rated power and burns out. Two ways to tell them apart: measure the resistance, or look at the leads. Green and yellow is the 12V pin, blue and yellow is the 24V pin.

Does the glow plug run the whole time the heater is on?

No — only during start-up, roughly the first minute. Once the flame is self-sustaining the controller drops the pin out and the flame sensor takes over. A pin that stays energised means the heater is failing to establish a flame, which points at fuel delivery or the screen.

My glow plug tests fine but the heater still will not light. What now?

Check the screen, then the fuel, then the ground. A pin that reads correct resistance and pulls its rated 70 W is working. The usual order after that is a carboned screen, air in the fuel line or a tired fuel pump, then a poor ground back to the control unit.