Heat Meter Error Codes: Meanings by Brand and Solutions
What do Err and E codes, the warning triangle and the battery symbol on a heat meter display mean? Code tables for Minol Zenner, Danfoss, CEM, Honeywell and Calmet based on the manufacturers' manuals, safe steps and complaint testing.
If you see a code starting with Err or E or a warning triangle on the heat meter display instead of the reading, the meter has detected a problem. Some of these codes indicate faults that require service, such as the battery or a sensor; others indicate conditions in the installation, such as air or reverse flow. In this guide we explain, in our own words, the error codes in the manufacturers' manuals for the heat meters sold on our site and describe what to do in each case. For reading the normal values on the display, see our guide How to Read a Heat Meter.
What Problems Do Warning and Error Symbols Indicate?
Although brands number their codes differently, the problems they indicate fall into the same groups:
| Problem group | What does it mean? | Example codes |
|---|---|---|
| Temperature sensor | Supply or return sensor cannot be read, cable broken or short-circuited | Minol Zenner 1–6 · Danfoss E06–E08 · CEM Err 1–5 · Honeywell ERR 2–5 · Calmet 11, 12, 15, 16 |
| Air, no water, no flow | The measuring tube is not completely full or there is air in the water | Minol Zenner 20, 40 · CEM Err 6 · Honeywell ERR 6 |
| Reverse flow | Water passes through the meter in the reverse direction | Minol Zenner 30 · Danfoss E12 · CEM Err 0 · Honeywell ERR 0 · Calmet 10 |
| Battery | Battery voltage has dropped or battery life is ending | Minol Zenner 7, 1000 · Danfoss E03–E05, E15 · Honeywell battery symbol |
| Communication | Problem in the radio or communication module | Minol Zenner 800 · Danfoss E32 |
| Tampering | Calculator unit or body has been opened | Danfoss E13 · Qundis cOPEn |
| Internal fault | Error in the electronics or the flow measuring unit | Minol Zenner 8, 9, 10, 100 · Danfoss E01, E02, E09, E10 · Calmet 13 |
A warning triangle that appears briefly and then disappears does not always mean a fault. ZENNER states that the triangle may appear temporarily in special operating conditions and that the service provider should be informed if it remains for a long time.
Error Code Tables by Brand
The tables are based on the manufacturers' installation and user manuals; the explanations are in our own words. Most of the tasks in the What to do column are for the service provider or installer.
Minol Zenner C5 IUF and C5 ISF
The code is read on the Err display in level 3. If there is more than one error, the sum of the codes is shown: 1005 means that errors 1000 and 5 are present together. Codes 10–50 exist only on the ultrasonic C5 IUF.
| Code | Meaning | Possible cause | What to do |
|---|---|---|---|
| 1, 2 | Below / above the temperature measuring range | Sensor fault or temperature out of range | Service should check the sensors |
| 3–6 | Short circuit / break in the return (3, 4) or supply (5, 6) sensor | Sensor or its cable damaged | Service should check the sensors |
| 7, 1000 | Low battery voltage / end of battery life | Battery running out | Replace the meter, or the battery if permitted |
| 8, 9, 10, 100, 800 | Hardware, measuring system or radio interface error | Internal fault | Replace the meter |
| 20 | No water in the measuring tube | Installation empty or pressure low | Check the operating pressure |
| 30 | Reverse flow | The meter may be installed in the wrong direction | Check the installation direction |
| 40 | Air in the water | The installation has not been vented | Vent the installation |
| 50 | Value outside the overload range | Flow exceeds the meter's capacity | Check the meter size |
| 2000 | The initial verification period defined in the meter has expired | The period is defined per country | The manufacturer foresees replacement; re-verification periods follow local rules (5 years in Türkiye, for example) |
Danfoss SonoSafe 10 and SonoSelect 10
Both models use the same manual. The code appears on the alarm display in loop 1 together with a warning triangle. The manual gives the meaning of the codes but does not state the cause for most of them.
| Code | Meaning | Possible cause | What to do |
|---|---|---|---|
| E03, E04, E05 | Battery empty (less than 1 month) / voltage low / battery low (less than 12 months) | End of battery life | Plan battery or meter replacement |
| E15 | Battery consumption too high | Not stated in the manual | Report to service |
| E06, E07, E08 | Supply / return temperature error; temperature out of range | Sensor, its connection or operating condition | Service should check the sensors |
| E01, E02, E09, E10, E16 | System, electronic board or transducer error; display overflow | Internal fault | Report to service |
| E11, E14 | Outside the measuring range / flow above the upper limit | Flow exceeds the meter's range | Check the meter size and flow |
| E12 | Negative (reverse) flow | Water passing in the reverse direction | Check the installation direction |
| E13 | External tamper alarm | The calculator unit cover has been opened | Can only be reset with a service tool |
| E18 | Dead band error on a heating–cooling meter | Not stated in the manual | Report to service |
| E32 | Communication module error | Module battery depleted or pulse setting incorrect | Service should check the module |
CEM CM-HR
According to the CEM manual, the Err message is shown continuously on the display while there is an error.
| Code | Meaning | Possible cause | What to do |
|---|---|---|---|
| Err 0 | Reverse flow | The meter may be installed against the flow direction | Check the installation direction |
| Err 1 | Sensors installed the wrong way round | Hot and cold line sensors swapped | Service should check the sensor positions |
| Err 2, Err 4 | Hot / cold line sensor not detected | The sensor cable may be broken | Service should check the sensor |
| Err 3, Err 5 | Short circuit in the hot / cold line sensor | The sensor circuit may be faulty | Contact an authorized service provider |
| Err 6 | No flow | Air in the installation, pipe not completely full or no flow | Vent the system and check the flow |
Honeywell (Resideo) EW700
In Honeywell's user instructions for the EW700 series, the codes start with ERR; the battery status is shown with a separate symbol.
| Code | Meaning | Possible cause | What to do |
|---|---|---|---|
| ERR 0 | Reverse flow | Water passing in the reverse direction | Check the flow direction |
| ERR 2–5 | Open circuit / short circuit in the supply (2, 3) or return (4, 5) sensor | Sensor or its cable | The manufacturer foresees meter replacement |
| ERR 6 | Air inside the meter | The installation has not been vented | Vent the system |
| Empty battery symbol | Battery weak | End of battery life approaching | Battery should be replaced by service |
Calmet PM02
According to the technical document of the manufacturer FNF Teknoloji, an information code flashes on the display while the error persists and disappears automatically when the error clears. The last 10 errors are stored with date and time in the 5-ERROR menu. The document does not separately give the cause and solution of the codes.
| Code | Meaning | Possible cause | What to do |
|---|---|---|---|
| 1–6, 8 | Ultrasonic measuring circuit errors (calibration, signal, timeout, unreliable measurement) | Not stated in the document | Report to service if it persists |
| 7, 13 | Parameter error / memory error | Internal fault | Report to service |
| 9, 10, 14 | No flow / reverse flow / maximum flow exceeded | Installation or installation direction | Have it checked if it persists while the heating is on |
| 11, 12, 15, 16 | Sensor cable broken, short circuit or T1/T2 out of range | Temperature sensor | Service should check the sensors |
Qundis Q caloric 5.5 (Heat Cost Allocator) and Other Models
According to the Qundis data sheet, on the heat cost allocator an error is shown with Err and a digit, the end of battery life with bAt00, and opening of the housing or tampering with the text cOPEn or a small letter c on the display. Report these conditions to your metering company. For İntegral UK-PLUS and Novus Digitermo DTL, the manufacturers have not published an error code list online; you can photograph the code on the display and send it to us.
What Can You Do as a User?
- Take a photo of the display; note the code, the date and the reading on the main display together with its unit.
- Watch whether the code disappears within a few minutes; temporary warnings may clear by themselves.
- Check that the heating is running and the radiators are warming up. In case of an air warning, the installation should be vented by the building caretaker or an installer; for the radiators in the apartment, see our bleeding radiators guide.
- Report the situation to the building management or your meter reading company. For battery warnings, see our Heat Meter Battery guide.
Why You Must Not Touch the Seal or the Meter Interior
Do not dismantle the meter body, the calculator unit cover, the sensors or the cables yourself; do not break the seals. Under Türkiye's Heat Meter Inspection Regulation, for example, a meter without a stamp, or whose stamp or body has evidently been tampered with, is not re-verified. The manufacturers take the same line: Honeywell treats removal of the seal as tampering, Calmet states that a meter with a broken seal cannot be used as a basis for billing, and Danfoss gives a tamper alarm when the cover is opened.
When to Call Service, When to Replace
- Monitor: A warning triangle that appears briefly and disappears.
- Installation check: Air, no water or reverse flow codes. For these codes, the manuals ask you first to check the pressure, air and installation direction.
- Service: Sensor codes and warnings that remain on the display.
- Replacement: Hardware and internal fault codes for which the manufacturer says replace the meter, and end of battery life on models whose battery cannot be replaced. Models of the same size and length are in our Heat Meters and ultrasonic heat meter categories; installation parts are in our heat meter spare parts category.
Complaint Testing When You Suspect Incorrect Measurement
If you suspect that the meter is measuring incorrectly even though there is no error code on the display, you can request a test of the meter. The procedure depends on national rules. In Türkiye, for example, under the Heat Meter Inspection Regulation, this application is made in writing to an authorized service by the user of the meter or by a person financially affected by the cost allocation. The service first checks the stamp and for tampering, then tests the meter; if the error is within the permissible limits, the meter is accepted as correct, otherwise it is repaired and adjusted. If the application comes from the user, the costs are borne by the user regardless of the result. For the process, see our Heat Meter Re-verification and Calibration page.
Frequently Asked Questions
My heat meter shows Err. What should I do?
Photograph the code and the reading on the main display, check the meaning of the code in your brand's table and report it to the building management or your meter reading company. Do not open the meter and do not touch the seals.
What does the warning triangle on a heat meter mean?
It shows that the meter has detected a condition or an error. If it appears briefly and disappears, it is not always a fault; if it remains for a long time, the service provider should be informed.
Is consumption measured while the heat meter shows an error?
It depends on the code. With sensor, flow or internal fault codes, the measurement may be affected; persistent error codes should therefore be reported to the service provider without delay.
What causes a reverse flow error?
It occurs when water passes through the meter in the reverse direction. The manuals ask you to check the installation direction; CEM's manual states that the meter may have been installed against the flow direction. The check should be done by an installer or the service provider.
I think the meter is measuring incorrectly. What can I do?
You can request a test of the meter by applying in writing to an authorized service; the exact procedure depends on local regulations. If the meter is within the permissible error limits it is accepted as correct; otherwise it is repaired and adjusted.
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