Short answer: E13 on an HLN diesel heater means no flame was detected during the start phase — the heater tried to ignite (twice) and combustion never established. On 8kW rotary-switch models the blink code is 01101. E13 often comes with white smoke from the exhaust: that is unburned fuel. The checklist below is the factory order — work top to bottom.

First: is there actually a flame?

If the heater IS burning but still throws E13, the flame sensor is not seeing it — measure the flame-sensor resistance against the table in the manual before touching anything else. In most cases, though, there is genuinely no flame, so continue below.

The factory checklist, in order

1. Combustion air intake and exhaust. Check both lines for blockage, kinks or crushed sections — insect nests, road debris and snow are the classics. Quick test: remove both tubes and try a start. If it lights cleanly, the problem is in one of the lines.
2. Fuel grade vs temperature. Summer diesel gels in the cold and stops atomizing. In winter run winter-grade diesel or an anti-gel additive.
3. Glow pin screen and vent hole. Remove the glow pin and inspect the screen — carbon fouling here is the single most common cause. Clean or replace the screen (it is a yearly service item) and check the small vent hole is clear.
4. Is the fuel pump pulsing? You should feel/hear the tick during start. No pulses → check the pump harness for an open circuit; replace the pump if necessary.
5. Fuel quantity test. Run the factory fuel-delivery measurement (rapid-pump mode into a graduated cylinder — procedure and target volume are in the service manual). Under-delivery points to the filter, lines or pump.
6. Carbon on the glow pin. Clean off any deposits before refitting.

E13 with white smoke?

White smoke means unburned fuel — flooded chamber, altitude, or airflow restriction. Full guide with the 2-minute flooded-chamber fix: Why Is My Diesel Heater Blowing White Smoke?

FAQ

The heater starts, runs a few minutes, then dies — is that E13?
That is usually E14 (combustion interruption after a successful start). E13 is specifically a failure during the start phase.

How many ignition attempts does the heater make?
Two. If the second attempt also fails to establish combustion, the heater locks out and reports the fault.

Is E13 dangerous?
The heater shuts fuel off when ignition fails. Clear any flooded fuel before repeated restart attempts — see the white-smoke guide above.

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