Error Codes of STS Prepayment Meters

STS (Standard Transfer Specification) prepayment meters take digital medium as information exchange media. Users load in pre-purchased credit and then the meters take credit as their billing to realize the functions of active energy measuring and prepayment control and realize remote communication and remote control via module.
Local power companies or utilities use prepayment meters to avoid debts by charging power bills in advance. Additionally, prepayment smart meters with automatic reading function reduces cost of manual collecting meter data.
For end-customers, they can check their meter load in real time to use power reasonably. They can also recharge meters in any place and any time, instead of going to local power company to pay for.

CLOU STS Prepayment Meters

We have many STS prepayment meters, such as CL730S22 and CL710K22. You can also find more information about prepayment meters here.

Single Phase Meter CL710K22
Single Phase Meter CL710K22
Three Phase Meter CL730S22
Three Phase Meter CL730S22

Differences between TOKEN and Meter Numbers

TOKEN numbers and meter numbers are two totally different things.
According to the STS standard, a TOKEN has only complete 20 digits.
While CLOU STS meters have 11 digits. Other CLOU meters also have 12 digits.
The length of meter numbers is customized.
When you input a Token by which the prepayment meter can not work, the meter will show error codes. Specific reasons are cited one by one as below. If your meter equips an UIU (User Interface Unit), error codes also shows on its LCD.

Error Codes Shown on CLOU Prepayment Meter

CLOU regulates prepayment meter error codes in a certain statement according to the IEC62055-41 chapter 7.1. Almost all CLOU prepayment meters have the same error codes.
Here takes error codes shown on the CL730S22 three-phase meter as an example.

Meter Display Information

  • OPEN Any meter cover was opened
  • DISTU Magnetic disturbance detected
  • OVER PO Power exceeds the limit
  • VOL-OVER Voltage is over allowed threshold
  • CUR-OVER Current is over allowed threshold
  • CUR-UNB Current unbanlance occured
  • N-DST Neutral line is disturbed
  • CT-BYPAS Meter is bypassed
  • CT-OPEN Meter current circuit is open
  • VOL-UNB Voltage is unbalanced
  • HIGH-TMP Temperature too high
  • LOW-PF Power factor too low

UIU Display Information

  • ACCEPT TOKEN accepted
  • REJECT TOKEN rejected. The 20-digit TOKEN input is not generated from the designated platform.
  • OLD TOKEN expired
  • USED TOKEN used
  • FULL Overflow error. The credit register in the payment meter would overflow if the token were to be accepted; the token is not accepted.
  • OK Operation accepted
  • Err_01 Error in manufacturer code. The Manufacturer Code value in the Class 1 token does not match the Manufacturer Code value for the Decoder.
  • Err_02 Key expired error. The TID (Token Identifier) value as record in the token is larger than the KEN (Key Expiry Number)stored in the payment meter memory.
    Solution: First, please check your meter KEN value if it has expansion space or not; If the number is already maximum, shift the TID and change the Base Date in the energy selling system into “2014” option.
  • Err_03 DDTK (Decoder Default Transfer Key) error. The Decoder has a DDTK value in the DKR (Decoder Key Register): a Transfer Credit token may not be processed by the Meter Application Process in accordance with the values given in credit.
  • Err_04 Overflow error. The credit register in the payment meter would overflow if the token were to be accepted; the token is not accepted. (Some meter types are showing Err_04 instead of FULL).
  • Err_05 Key type error. The key may not be changed to this type in accordance with the key change rules.
  • Err_06 TOKEN format error. One or more data elements in the token does not comply with the required format for that element. That’s say, to aviod this error, 20 digits of the TOKEN are correct and complete, and the TOKEN must be valid and unused. For example, the error shows when one only inputs 19 digits.
  • Err_07 TOKEN range error. One or more data elements in the token have a value that is outside the defined range of values defined in the application for that elements.
  • Err_08 TOKEN Function error. The particular function to execute the token is not available.
  • NULL Reserved

Troubleshooting to Pairing A UIU with A Meter

If something wrong happens while paring a UIU (User Interface Unit) with an energy meter, the following steps can be taken to initiate the UIU for troubleshooting.

  • Step1: Input “1593570” + “999” + “Enter” to initialize the UIU.
  • Step2: Input “1593570” + “11-digit meter number” + “Enter” to pair the meter with UIU.
  • Step3: Input “999” + “enter” to check the paired meter, and “12-digit address” will be displayed on the UIU.


So far, we have received a great number of comments about meter error codes and TOKEN. This article aims to at least provide a fundamental explanation to error codes.
For visitors who are finding information about them, wish this article can help you.
If you have more questions about error codes, just leave a comment below to discuss it.
Thank you for your reading and best wishes.

Editor's note: This article was originally published in November 2021 and has been updated for comprehensiveness.

86 Replies to “Error Codes of STS Prepayment Meters”
    1. Dear Vincent, thank you for your comment first. Please read the updated article again for the solution to your problem.

    1. You need to get a ‘clear tamper’ token, which can only be issued by your energy vending company.

    1. Your power company can read the log-file from the meter. With the log-file, they know what happened and when.

  1. My CLOU CIU unit is not accepting token units, ive replaced the batteries but its still the same. The screen was showing CU_ Unb what does this mean and what can i do to load the token units. Currents it is not working and its shows zero units? But its has units from prevous load and power is still there.

    1. Hi Nazir, thanks for your comment again. We’ve updated the article that now has answer for your problem. Plz read it.

  2. My cloug CIU is not loading units, ive replaced new batteries but ita still accepting. Its showing on the screen CUr_Unb. What does it mean and how to i solve it?

    1. Hi Nazir, thanks for your comment. We’ve updated the article that now has answer for your problem. Plz read it again.

  3. I’m a Electronics and Electrical Electrician, I worked on customers meter’s in my community when problem like this happen I always called the electrical company for problem solving on error like rejected token. Company will only talk about replacing it and to replace it gonna take a year or more. I’m surviving by customer, how can I get this problem solve without replacement. Pls help me, my family depends on me. It’s hard for employment in my country.

    1. Thank you for your question. All STS meters are rejecting tokens, when they have been issued for another meter number or by a vending system with a different SGC (supply group code). This is part of the STS security. There is no need to change the meter. The problem is related to the token vendor.

  4. I tried the above ti set up my meter but I keep getting rejected and failed as error message.

    1. I suppose, you have got a token which was generated for another meter. Talk to your energy provider and let them check.

  5. Thanks for this article for I am currently working on the different sts meters around and meaning of the error codes.

    What is the Solution when meter has DDTK Error?
    I awaits your response

    1. Thank you for the question. The meter needs to be assigned to the unique supply group code (SGC) of the vending power company.

  6. I get error 6 when I input my meter number on my cl710k22 prepaid meter how do I resolve it and am unable to load the token I bought please help me out of this thank you

    1. Please check your meter payment mode first. If still failed, please ask your local power company for more specific help, thanks.

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