E-04 on a diesel heater: fuel pump circuit fault
Updated
E-04 means the controller sees an electrical fault in the fuel pump circuit: the pump is disconnected, its wiring is open or shorted, or the pump has failed. It is not a low-fuel code. First check: the plug on the pump and the pump wires along their whole run.
Which controller do you have?
The same number means different faults on different controllers. Match yours to a sketch first. This meaning applies to the 5-button LCD, the B2010 and the Vevor M-button panel; on the Hcalory HC-A01 and on the rotary-switch LCD on Heatport and T4 heaters, the number 4 means something else.
- 5-button LCDE-01 … E-10 with two digits, on a black panel with five round buttonsThis page applies
- Vevor M-button panelE-xx flashing on a colour screen, four keys including M, voice promptsThis page applies
- Rotary knob, LEDsNo screen: an LED flashes a count, pauses, repeats
- LCD, E-2 … E-10E-2 … E-10, one digit after the dash, no E-1
- Rotary-switch LCD, E0 … E15E1, E2, E3 … with no dash, on an LCD switch you turn and press
- Knob LCD (Hcalory HC-A01)E-01 … E-10 on a colour LCD with one push-turn knob
At a glance
| Code | E-04 |
|---|---|
| Meaning | Fuel pump circuit fault: pump disconnected, wiring open or shorted, or pump failed |
| Most common cause | The manuals point to the pump plug and its wiring. Owner evidence is thin |
| Check this first | Reseat the plug on the pump and inspect the pump wires for damage |
| Evidence | Manuals and owner reports |
What E-04 means on each controller
| Code | Controller | Manual or brand | Meaning | Stated limit |
|---|---|---|---|---|
| E-04 | 5-button LCD | OnTrack Outdoor 5 kW Manual | Fuel pump failure Manual's remedy: Check the fuel pump and its connections for leaks, damage or oxidation. | Not stated |
| E-04 | 5-button LCD | D2/D4 parking heater (generic manual) Manual | Fuel pump fault Manual's remedy: Check whether the fuel pump is disconnected or short-circuit. | Not stated |
| E-04 | 5-button LCD | Hcalory M98 Manual | Oil (fuel) pump short circuit / open circuit Manual's remedy: Pump not connected properly or its line short-circuited/disconnected; pin socket on control board not firmly inserted; pump circuit disconnected or pump faulty. | Not stated |
| E-04 | Vevor M-button panel | Vevor XMZ-D1 / XMZ-D2 Manual | Oil (fuel) pump abnormality Manual's remedy: Check the pump plug for loose/false connection; check main wiring harness for disconnection; pump faulty - replace. | Not stated |
| E-4 | LCD, E-2 … E-10 | Vevor CY-5001/5002/5004, 5-key and 3-key LCD panels Manual | Oil (fuel) pump malfunction Manual's remedy: Check pump connection wires and connectors for damage, looseness, oxidation, short or open circuit. | Not stated |
| E-4 | LCD, E-2 … E-10 | Gasmate DH203 Manual | Fuel pump failure Manual's remedy: Contact service support for inspection or replacement of the fuel pump. | Not stated |
| E-4 | LCD, E-2 … E-10 | Liwolf all-in-one Manual | Fuel pump failure Manual's remedy: Inspect pump harness and connectors for damage, looseness, oxidation, short or open circuits. | Not stated |
| C4 | Rotary-switch LCD, E0 … E15 | T4 two-knob LCD switch Manual | Control switch Manual's remedy: Replace the control switch. | Not stated |
| E4 | Rotary-switch LCD, E0 … E15 | Heatport H2 / H4 (EnControl) Manual | Premature ignition identification Manual's remedy: Residual fuel in the heater (shutdown not completed, e.g. voltage drop): leave the heater in a warm, well-vented place to evaporate the fuel. | Not stated |
| E4 | Rotary-switch LCD, E0 … E15 | T4 two-knob LCD switch Manual | Premature ignition Manual's remedy: Restart the heater after verifying that the last improper shutdown left residual fuel causing premature ignition. | Not stated |
| E-04 | Knob LCD (Hcalory HC-A01) | Hcalory HC-A01 Manual | Air outlet temperature sensor failure Manual's remedy: Check whether the outlet air temperature sensor connector is loose; outlet sensor failed - replace the main board; main board failure - replace. | Not stated |
| E-04 F1 | B2010 (spanner button) | B2010 controller Manual | Fuel ('oil') pump short circuit | Not stated |
| E-04 F2 | B2010 (spanner button) | B2010 controller Manual | Fuel ('oil') pump open circuit | Not stated |
What does E-04 mean: is it the pump or the fuel?
It is the pump’s electrical circuit. All five manuals for these controllers describe E-04 as a wiring or pump fault, and none mentions the fuel level:
| Manual | What it lists under E-04 |
|---|---|
| OnTrack guide | Pump and its connections: leaks, damage, oxidation |
| Generic D2/D4 manual | Pump disconnected or short-circuited |
| B2010 | F1 pump short circuit, F2 pump open circuit |
| Vevor XMZ-D1 / XMZ-D2 | Pump plug loose, main harness broken, pump faulty |
| Hcalory M98 | Pump not connected, line shorted or broken, pin socket on the control board not pushed in, pump faulty |
All rows are from the manuals. Manual
One owner’s notes on these codes say the same in plainer words: E-04 only detects an open or a short in the pump circuit, so test the pump on its own and then look for a wiring fault. Owners
Owner evidence for E-04 is thin and no cause reaches three independent confirmations. What there is:
- One owner had E-04 with a silent pump; after removing and refitting the pump the code cleared. No longer-term result was posted, so this is not a confirmed fix. Owners
- A search excerpt of one owner’s post describes pump wiring that melted on the exhaust and blew the fuse, with E04 afterwards. The thread was not read in full and the excerpt shows no fix. Owners
- One owner traced a no-start to a pump connector wire that was not pushed home in its plastic plug. The code there was not E-04, but it is the kind of fault the manuals describe. Owners
What about air bubbles and priming?
Two owners in the same thread cleared an E-04 by priming, one of them after reseating an in-line filter that sat at an angle. Owners That does not fit the manuals’ electrical meaning, and nobody in the thread explained it. Treat it as unconfirmed. Air in the line, an empty tank and a blocked filter normally show as E-08 flame out or E-10, not E-04.
If you do prime, do it in short bursts and stop when fuel reaches the heater. Over-priming floods the burner. The Vevor M-button panel primes with a fixed 300 s countdown that ends by itself or when you press power. Manual See manual fuel priming.
How do I check the pump circuit?
Work from the pump back to the heater, with the power off.
- Reseat the plug on the pump. Pull it, look for oxidation and for a pin that has backed out of the plastic housing, and push it fully home. Manual Power up. If E-04 has gone, you are done. If not, go to step 2.
- Follow the pump wires along their whole run. Look for a crushed, chafed or melted section. The Hcalory M98 manual lists a pump line that is shorted or broken, and the one owner post about wiring melted on the exhaust is a reason to look hardest there. Manual Owners Damage found: go to step 5. No damage: go to step 3.
- Check the harness plugs at the heater. The Vevor manual lists a broken main harness, and the Hcalory M98 manual a pin socket on the control board that is not firmly inserted. Manual Reseat what you can reach without dismantling the heater. Still E-04: go to step 4.
- Read the sub-code if you have a B2010. F1 means a short circuit, F2 an open circuit. Manual See the F1, F2 and F3 page. A short points at the wiring or the pump; an open points at a plug, a broken wire or the pump.
- Decide between wiring and pump. One owner checked his pump with a meter and found the coil had continuity. Owners The manuals do not give a resistance figure for the pump. No continuity across the pump’s terminals, with its plug off, means the pump is open circuit. Continuity at the pump but E-04 on the controller points back to the wiring or the board.
If you are not sure, ask a technician. Repairing the wiring loom or replacing the control board goes beyond routine owner maintenance. A mistake here can cause a fuel or exhaust leak. Stop if anything is unclear.
How do I clear E-04?
The manuals give no reset step for E-04. With the circuit repaired, start the heater again. If it does not respond, see how to reset a locked-out heater.
When do I replace the fuel dosing pump?
When its plug and wiring are sound and the pump itself is open circuit, or when the manuals’ other causes are ruled out. The Vevor manual ends its E-04 list with replacing a faulty pump, and the Hcalory M98 manual also lists a faulty pump last. The T4 manual, under its own pump code E7, adds that the control board is a rare cause. Manual
Is E-04 the same on other controllers?
No. Panels that show E-4 with no leading zero also use it for the fuel pump. On the Hcalory HC-A01 knob LCD, E-04 is the air outlet temperature sensor and the pump fault is E-06. On the rotary-switch LCD on Heatport and T4 heaters, E4 is premature ignition and the pump fault is E7. Manual Check which controller you have.
Related questions
- Does E-04 mean the heater is out of fuel?
- No. Every manual for these controllers describes E-04 as a pump or pump-wiring fault: disconnected, open circuit or short circuit. Running out of fuel shows as a flame-out or ignition failure, E-08 or E-10 on the same table.
- Why do I get E-04 as soon as I plug the heater in?
- A code at power-up fits the manuals' electrical meaning: a loose plug, a broken wire or a short. Two owners in one thread did clear an E-04 by priming and reseating a filter, which the manuals do not explain, so check the wiring first.
- My pump clicks but I still have E-04. Is the pump bad?
- The sources do not settle that. The Vevor and Hcalory manuals list a faulty pump last, after the plug and the harness. On a B2010, the sub-code helps: F1 is a short circuit and F2 an open circuit.
Where to go next
Sources
Everything on this page is compiled from the documents and discussions below. We summarise them in our own words; follow the links for the originals.
- OnTrack Outdoor: diesel heater troubleshooting guide (PDF) (cdn.shopify.com)
- D2/D4 parking heater 12 V/24 V user manual, Alza import (PDF) (dwn.alza.cz)
- B2010 controller operating manual V1.2 (PDF) (cdn.shopify.com)
- Vevor diesel heater manual, XMZ-D1 / XMZ-D2 (PDF copy) (tuitam.pl)
- Hcalory air heater user manual, M98 (PDF) (cdn.shopify.com)
- Hcalory HC-A01 toolbox heater user manual (archived transcription) (web.archive.org)
- T4 diesel air heater user manual, Alza import (PDF) (dwn.alza.cz)
- Heatport H2 / H4 EnControl user manual v1.00 (PDF) (cdn.shopify.com)
- Vevor diesel heater manual, CY-5001 / CY-5002 / CY-5004 (PDF copy) (xlrzbfnheqpszgtyhdkh.supabase.co)
- Owner report: E-04 at power-up after a controller swap, cleared after priming (Expedition Portal forum) (forum.expeditionportal.com)
- Owner report: E-04 twice, cleared by reseating the filter and priming (Expedition Portal forum) (forum.expeditionportal.com)
- Owner notes: E-04 only detects an open or short in the pump circuit (drive2.ru) (drive2.ru)
- Owner report, no follow-up: E-04 with a silent pump, cleared after refitting the pump (Reddit r/dieselheater) (reddit.com)
- Owner post, search excerpt only: E04 after the pump wiring melted on the exhaust (Reddit r/vandwellers) (reddit.com)
- Owner report: silent pump with coil continuity, piston stuck (Reddit r/dieselheater) (reddit.com)
- Owner report: pump connector wire not pushed home in its plug (Reddit r/dieselheater) (reddit.com)