Espar (Eberspächer) Furnace: “020 / 021 / 022”
warning RV furnace fault codes
What it means
Glow plug electrical fault: 020 = open circuit / interruption (broken plug or disconnected wire), 021 = short circuit to ground, 022 = short circuit to battery positive. The control unit detects an abnormal glow plug circuit and stops.
Most likely causes
- Failed glow plug (open element) for code 020 most likely
- Damaged, chafed, or pinched glow plug wiring causing a short (021/022) common
- Corroded or loose glow plug connector common
Safe checks you can do yourself
- Inspect the glow plug connector and wiring for damage, corrosion, or chafing.
- Confirm the connector is fully seated.
- Look for wiring pinched against metal that could cause a short.
How to reset / clear 020 / 021 / 022
- Switch off and on to retry.
- If the circuit fault persists, the glow plug and its wiring need testing/replacement by an installer.
When to call a technician
If wiring and connector look good but the fault persists, the glow plug or control unit needs professional diagnosis.
Applies to
Airtronic D2 · Airtronic D4 · Airtronic D4S · Airtronic B4
FAQ
What does Espar (Eberspächer) Furnace code "020 / 021 / 022" mean?
Glow plug electrical fault: 020 = open circuit / interruption (broken plug or disconnected wire), 021 = short circuit to ground, 022 = short circuit to battery positive. The control unit detects an abnormal glow plug circuit and stops.
How do I reset Espar (Eberspächer) Furnace 020 / 021 / 022?
Switch off and on to retry. If the circuit fault persists, the glow plug and its wiring need testing/replacement by an installer.
What is the most common cause of 020 / 021 / 022 on a Espar (Eberspächer) Furnace?
The most likely cause is failed glow plug (open element) for code 020.
Related · Espar (Eberspächer) furnace
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Overheat shutdown. The temperature measured at the overheat … 019
Glow plug (glow pin) energy too low: the glow plug is not de… 047 / 048
Metering (fuel dosing) pump fault: 047 = short circuit / ove… 050
Operating lockout: too many unsuccessful start attempts. Aft… 052
Unsuccessful start (no flame established). The heater attemp…
Sources
- Eberspacher Airtronic Fault Codes — Codes 20 (open), 21 (short to ground), 22 (short to battery+) (Le Tonkinois (independent Eberspacher reference))
- Find and clear Espar Airtronic fault codes and Eberspacher Hydronic fault codes — Glow plug issues, P000210/P000211/P000212 (020/021/022) (Heatso)
Note: Newer controllers map these to P000210/P000211/P000212.
● Last verified 2026-06-29 · compiled from manufacturer documentation. Codes can vary by model year — always cross-check your unit’s manual.