E-02 on a diesel heater: overvoltage
Updated
On the 5-button LCD and the B2010, E-02 means the supply voltage is too high. The B2010 manual sets the limit at 17 V on a 12 V system. First check: read the supply voltage on the controller and at the battery, with any charger or solar controller running.
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 and the B2010; the Vevor M-button panel manual lists no E-02 and reports high voltage as E-01.
- 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 prompts
- 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-02 |
|---|---|
| Meaning | Supply voltage too high (Hcalory M98: voltage fault on 24 V models, high or low) |
| Most common cause | The manuals point to the charging source. Owner reports do not isolate a cause |
| Check this first | Read the supply voltage on the controller and at the battery while charging sources are on |
| Evidence | Manuals and owner reports |
What E-02 means on each controller
| Code | Controller | Manual or brand | Meaning | Stated limit |
|---|---|---|---|---|
| E-02 | 5-button LCD | OnTrack Outdoor 5 kW Manual | Power supply overvoltage Manual's remedy: Reduce supply voltage (discharge the battery). Detail page: check voltage at battery before/during start-up; use a charge controller so external sources do not overcharge; discharge or replace battery. | Not stated |
| E-02 | 5-button LCD | D2/D4 parking heater (generic manual) Manual | Overvoltage Manual's remedy: Reduce the supply voltage. | Not stated |
| E-02 | 5-button LCD | Hcalory M98 Manual | Supply voltage fault, 24 V model Manual's remedy: Check the power supply voltage / external power supply. | 24 V model: voltage higher than 32 V or lower than 20 V |
| E-2 | LCD, E-2 … E-10 | Vevor CY-5001/5002/5004, 5-key and 3-key LCD panels Manual | Power supply voltage out of range Manual's remedy: Check the battery or generator is working properly; check whether the fuse is aged. | Normal range: 24 V controller 18-32 V; 12 V controller 9-16 V |
| E-2 | LCD, E-2 … E-10 | Gasmate DH203 Manual | Over-voltage or under-voltage Manual's remedy: Check battery charge level and condition; fuse condition and connection; cable condition and excessive voltage drop. | Supply voltage detected outside 9-16 V |
| E-2 | LCD, E-2 … E-10 | Liwolf all-in-one Manual | Power supply voltage range Manual's remedy: Check voltage range; inspect battery or generator; check whether the fuse is broken. | 24 V: 18-32 V; 12 V: 9-16 V |
| C2/C7 | Rotary-switch LCD, E0 … E15 | T4 two-knob LCD switch Manual | Control switch Manual's remedy: Verify the control switch is properly connected to its wiring; replace the control switch if necessary. | Not stated |
| E2 | Rotary-switch LCD, E0 … E15 | Heatport H2 / H4 (EnControl) Manual | Flame extinction Manual's remedy: Same checks as E1. | Not stated |
| E2 | Rotary-switch LCD, E0 … E15 | T4 two-knob LCD switch Manual | Flame off (repeated 3 times) Manual's remedy: Remove bubbles from the fuel line; replace the pump if output is insufficient; check and clean air intake and exhaust of carbon deposits. | Flame-out repeated 3 times |
| E-02 | Knob LCD (Hcalory HC-A01) | Hcalory HC-A01 Manual | Lack of oil (fuel) and stalling Manual's remedy: Check the fuel tank for lack of fuel. | Not stated |
| E-02 | B2010 (spanner button) | B2010 controller Manual | Over voltage | 12 V system: higher than 17 V; 24 V system: higher than 32 V |
What does E-02 mean on my controller?
The manuals differ, so find your row.
| Manual | What E-02 means |
|---|---|
| OnTrack guide, generic D2/D4 manual (5-button LCD) | Supply overvoltage. No figure given |
| B2010 | Over voltage: above 17 V on a 12 V system, above 32 V on a 24 V system |
| Hcalory M98 | Voltage fault on 24 V models: above 32 V or below 20 V |
| Vevor XMZ-D1 / XMZ-D2 | Not listed. E-01 covers any abnormal voltage, including above 18 V |
All four rows are from the manuals. Manual
The Hcalory M98 row matters if you own a 12 V Hcalory with the 5-button panel: that manual uses E-01 for 12 V models and keeps E-02 for 24 V models.
What do the manuals say causes it?
The OnTrack guide points to the charging side: an external source overcharging the battery. Its remedy is to check the voltage at the battery before and during start-up and to use a charge controller. Manual The generic D2/D4 manual only says to reduce the supply voltage. Manual The B2010 manual gives the limits and no remedy. Manual
Why do I get E-02 when the voltage reads 11 or 12 V?
The sources do not explain it. One owner saw E-02 with 11.8 V on the display while starting, after 18 trouble-free months. In that thread another owner had the same code and cured it only by fitting a different battery, without finding out why. Owners Three more threads describe E-02 at about 11-12 V, but they were seen only as search excerpts and none shows a confirmed fix. Commenters in those excerpts suggest a low battery or a bad voltage reading on the board. Those are guesses, not findings.
So there is no confirmed cause to give you here. What the reports support is a cheap test: try a different, fully charged battery.
Is my lithium battery too much for the heater?
No confirmed case of a lithium battery causing an overvoltage code on one of these heaters was found. One owner’s controller misbehaved on a lithium battery resting above 13 V and behaved again once it fell below 13 V, but the code on screen was E-07 with a wiring icon, not E-02. Owners More detail is on lithium batteries and voltage errors.
How do I check it?
- Read the supply voltage. On the 5-button LCD press OK until the supply voltage shows; on the B2010 the confirm button steps to it. Manual Compare it with a meter at the battery terminals. If both are far below the manual’s limit, you have the unexplained pattern above: go to step 3.
- Look at what is charging the battery. If the reading really is high, switch off the charger, solar controller or engine and try again. The OnTrack guide’s remedy is a charge controller on external sources. Manual
- Try another charged battery. One owner’s E-02 went away this way. Owners
- Check the 12 V / 24 V setting, with caution. The Hcalory M98 manual shows an operating-voltage item (12 or 24) in the 5-button panel’s password menu, changeable only with the heater off, and the B2010 has a 12 V / 24 V position on its password page. Manual No source ties a wrong setting to E-02. The one confirmed owner case of a wrong setting produced E-01. See the hidden settings menu and write down every original value first.
How do I clear E-02, and when do I stop?
The manuals give no reset step for E-02. Start the heater again once the supply is in range; if it stays locked, see how to reset a locked-out heater. If E-02 returns on a known-good battery with the voltage in range, the controller or main board is the remaining suspect, and no owner report confirms which.
If you are not sure, ask a technician. Replacing the control board goes beyond routine owner maintenance. A mistake here can cause a fuel or exhaust leak. Stop if anything is unclear.
Is E-02 the same on other controllers?
No. Panels that show E-2 with no leading zero use it for voltage out of range in either direction (9-16 V on a 12 V controller in the Vevor CY manual). On the Hcalory HC-A01 knob LCD, E-02 means the heater ran out of fuel. Manual Start at the controller list if you are not sure which panel you have.
Related questions
- Why does my heater say E-02 when the voltage reads 11.8 V?
- The research behind this page does not answer that. One owner saw E-02 with 11.8 V on the display while starting, and a second owner in the same thread cured the same code by fitting a different battery without learning why. Three more threads with this symptom were seen only as search excerpts. None isolates the cause.
- Will a lithium battery cause E-02?
- No confirmed case was found. One owner's controller misbehaved on a lithium battery resting above 13 V, but the code it showed was E-07, not E-02. The upper limits the manuals print are 17 V (B2010) and 18 V (Vevor XMZ, and Hcalory M98 for 12 V models).
- My Vevor shows E-02 but the manual has no E-02. What now?
- The Vevor XMZ-D1 / XMZ-D2 manual lists no E-02 and uses E-01 for any abnormal voltage. If you have a different Vevor panel, identify it first: on panels that show E-2 with no leading zero, E-2 means voltage out of range in either direction.
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)
- Hcalory air heater user manual, M98 (PDF) (cdn.shopify.com)
- Vevor diesel heater manual, XMZ-D1 / XMZ-D2 (PDF copy) (tuitam.pl)
- Vevor diesel heater manual, CY-5001 / CY-5002 / CY-5004 (PDF copy) (xlrzbfnheqpszgtyhdkh.supabase.co)
- Hcalory HC-A01 toolbox heater user manual (archived transcription) (web.archive.org)
- Owner report: E-02 with 11.8 V while starting, another owner cured it with a different battery (Reddit r/dieselheater) (reddit.com)
- Owner post, search excerpt only: E-02 with 11 V on the display (Reddit r/dieselheater) (reddit.com)
- Owner post, search excerpt only: E-02 on a power station (Reddit r/dieselheater) (reddit.com)
- Owner post, search excerpt only: E-02 on a car battery at 12 V (Reddit r/dieselheater) (reddit.com)
- Owner report: controller misbehaved on a lithium battery above 13 V, code shown was E-07 (Reddit r/dieselheater) (reddit.com)
- Owner report: E-01 cleared by setting the controller to 12 V (Expedition Portal forum) (forum.expeditionportal.com)