E-01 on a diesel heater: undervoltage at start-up

Why does my heater show E-01 when the battery is full?

On the 5-button LCD and the B2010, E-01 is undervoltage. On the Vevor M-button panel the same code covers any abnormal voltage, too low or too high. Manual What counts is the voltage at the heater while the glow plug is drawing its start-up current, not what the battery reads at rest.

What owners found, most common first:

• Thin or long supply cable. Three owners in three threads cured E-01 (one wrote it as E-1) by cutting the supplied lead to length or swapping it for heavier cable. Two more fixed a low-voltage start failure the same way without naming the code. Owners One of the first three saw the voltage sag to 7.9 V on cheap leads. Another saw 8-9 V at start through a cigarette-lighter plug. Owners
• Power-station and cigarette-lighter sockets. Five owners in four threads had trouble on a power station’s 12 V output. Two could not start or run the heater from it, one got intermittent error codes, one needed the maker’s regulated 12 V cable, and one still tripped the breaker in real cold after dropping the lighter plug. Two of the five name a 10 A limit. Owners The Vevor XMZ manual asks for a 12 V supply of 15 A or more, and the OnTrack guide says the cable must be sized for a start-up draw of up to 12 A. Manual
• Weak or small battery. One owner got E-01 with the battery down at 11.2 V after hours on high. Another could only keep the heater running with the engine on and concluded the battery was too small; that owner did not name the code. Owners
• Controller set to 24 V. One owner cleared E-01 after a controller swap by setting the new controller to 12 V. A second had E-01 with 12.7-12.8 V on the display and nothing running, and a replacement controller cured it. The cause in that second case was not proven. Owners

What voltage triggers E-01?

The manuals do not agree, so read the line for your controller.

All five rows are from the manuals. Manual

How do I find where the voltage is lost?

1. Read the voltage on the controller while the heater starts. On the 5-button LCD, press OK until the supply voltage shows. On the B2010 the confirm button steps to it. On the Vevor M-button panel, hold up and down for 3 s with the heater on and go to item 004. Manual If the figure falls sharply when the start begins, go to step 2. If it stays healthy and E-01 still appears, go to step 5.
2. Measure at the battery terminals before and during the start. This is the OnTrack guide’s first check. Manual If the battery itself drops, charge it or test it. If the battery holds but the controller reading collapses, the loss is in between: go to step 3.
3. Check the cable and every joint. The OnTrack guide says to check cable size and length for voltage drop, and the Vevor manual says to check that the main harness connector is not loose. Manual Owners fixed it by cutting out surplus cable, fitting heavier cable straight to the battery and dropping the cigarette-lighter plug. Owners
4. On a power station, leave the lighter socket. One owner whose power-station socket could not fire the glow plug ran the same heater from a small car battery. Another needed the maker’s regulated 12 V cable. Owners Starting with the engine running is a workaround, not a repair.
5. Check the 12 V / 24 V setting. The Vevor manual says to check that the heater’s voltage type matches the vehicle. Manual The 5-button LCD keeps a supply-voltage item in its PIN menu, and the B2010 keeps one on its password page: see the hidden settings menu. Write down every original value before changing anything.

Lithium batteries and power stations have their own page: lithium batteries and voltage errors.

How do I clear E-01?

None of these manuals gives a reset step for E-01. Once the voltage at the heater holds through the glow phase, start the heater again. If it stays locked, see how to reset a locked-out heater.

When should I stop and replace something?

Replace the battery if it sags at its own terminals when charged. If the heater sees a healthy voltage through the whole start and still shows E-01, the suspects left are the controller and the main board. Only one owner report covers that case.

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-01 the same on other controllers?

No. On the Hcalory HC-A01 knob LCD, E-01 is a start-up failure and the manual points to the fuel pump and fuel line. On the rotary-switch LCD of Heatport and T4 heaters, E1 is a failed ignition and the voltage fault is E3. Manual If your panel looks different, start at the controller list.