Short answer: E19 on an HLN diesel heater means the glow pin (ignition plug) current is too high — a short circuit in the plug or harness, or carbon build-up dragging its resistance down. On 8kW rotary-switch models without a screen, the same fault is flashed as blink code 10011. Cleaning the carbon is often the whole fix.

What E19 means

The ECU monitors the current through the glow pin. Too much current means the resistance is too low — either a genuine electrical short (damaged harness, shorted plug) or carbon deposits on the ceramic plug and vaporizer mesh creating a conductive path. Carbon on the mesh is a classic symptom on heaters that have run rich (restricted intake, worn parts, poor fuel).

Factory diagnosis

1. Check the glow pin harness for damage; make sure it is properly routed and connected. Check the harness for continuity.
2. Remove the plug and clean the carbon from the ceramic plug and the vaporizer mesh.
3. If cleaning does not restore operation, replace the plug and mesh.
4. If the fault persists with a new plug, test the ECU and replace it if necessary.

Reference: healthy glow pin resistance (at 20 °C)

• Air heaters: 12 V — 0.42 to 0.7 Ω; 24 V — 1.2 to 2.0 Ω
• Coolant heaters: 12 V — 0.4 to 0.6 Ω; 24 V — 1.2 to 2.0 Ω

FAQ

Why did carbon build up in the first place?
Carbon means incomplete combustion — commonly a restricted combustion-air intake or exhaust, running long periods on the lowest setting, or poor fuel. Fix the cause, or the carbon (and E19) will return.

What's the difference between E18 and E19?
E18 is an open circuit; E19 is a short / current too high. See the E18 guide for the resistance test procedure.

My 8kW heater has no screen — how do I see this code?
Count the status-light flashes: E19 is 10011 — one long, two short, two long (long = 1, short = 0).

All HLN fault codes in one place: HLN Diesel Heater Error Codes Explained (E01–E32). Source: HLN factory service manual (2026 revised editions).