# On Call Extra Error Codes & Troubleshooting Guide: E0–E6, E8, E9, HI/LO & Strip Errors **By Dr Pramod kumar** · 2026-09-25 If your **On Call Extra glucometer** displays an error such as **E0, E1, E2, E3, E4, E5, E6, E8 or E9**, the message can help identify whether the problem relates to meter startup, calibration, test-strip handling, blood application, battery condition or meter electronics. On Call Extra also displays separate messages for **high or low glucose results, operating-temperature problems, data-transfer faults and sample re-dosing errors**. This guide explains the main **On Call Extra error codes and troubleshooting steps**, including what to do when the meter does not recognise a strip, the countdown does not begin, the sample is insufficient or the meter displays HI or LO. For the complete meter and strip overview, first see: [**On Call Extra Glucometer & Test Strips Complete Guide**](/blogs/knowledge-hub/on-call-extra-glucometer-test-strips-complete-guide) . * * * ## On Call Extra Error Codes: Quick Reference Display Likely Cause What to Do **E-0** Power-on self-check error Remove the battery for about 30 seconds, reinstall it and restart the meter. **E-1** Internal calibration-check error Turn off the meter or remove the strip, then restart and retest. **E-2** Test strip removed during testing Repeat with a new strip and leave it fully inserted until testing is complete. **E-3** Blood or control sample applied too early Repeat with a new strip and wait for the blood-drop / strip-ready symbol. **E-4** Used, contaminated or unsuitable strip Discard the strip and repeat with a new compatible On Call Extra strip. **E-5** Insufficient sample or late sample re-dosing Repeat correctly; if re-dosing is used, apply the second sample within the permitted short window. **E-6** Battery too low to continue testing Replace the battery before repeating the test. **E-8** Meter electronics failure Restart if appropriate; if the error persists, stop testing and seek product support. **E-9** Wrong strip, damaged strip or calibration problem Confirm you are using an On Call Extra strip and repeat with a new undamaged strip. **E-10** Data communication failure Check the applicable data-transfer connection/software. **E-12** Data cable connected while meter is waiting for sample application Disconnect the data cable, remove the strip and restart testing. **Important:** Use a fresh test strip whenever the manufacturer instructions tell you to repeat the test with a new strip. * * * ## On Call Extra E0 Error – Power-On Self-Check Error **E-0**, also commonly searched as **E0** or **On Call Extra error 0**, indicates a problem during the meter's power-on self-check. ### How to troubleshoot E0 1. Turn the meter off. 2. Remove the battery. 3. Wait approximately 30 seconds. 4. Reinstall the battery correctly. 5. Turn the meter on again. If E-0 continues after restarting the meter, do not repeatedly consume test strips while attempting to clear the error. Contact the appropriate supplier or technical-support channel. * * * ## On Call Extra E1 Error – Internal Calibration Check **E-1** indicates that the meter encountered an internal calibration-check problem. ### What to do for E1 1. Turn the meter off or remove the current test strip. 2. Restart the meter. 3. Insert a fresh compatible On Call Extra Test Strip. 4. Repeat the test according to the normal procedure. If E-1 repeatedly returns, discontinue repeated strip use and obtain technical support. * * * ## On Call Extra E2 Error – Strip Removed During Testing **E-2** means that the test strip was removed or lost proper contact with the meter while a test was in progress. ### How to fix E2 1. Discard the interrupted strip. 2. Insert a new compatible On Call Extra strip fully into the strip port. 3. Apply the sample only after the meter is ready. 4. Leave the strip in place until the result is displayed. Do not pull, move or partially eject the strip while the meter is counting down. * * * ## On Call Extra E3 Error – Sample Applied Too Early **E-3** occurs when blood or control solution is applied before the meter is ready to receive the sample. After inserting the test strip, wait for the appropriate **blood-drop / strip-ready symbol** before applying blood. ### How to correct E3 1. Discard the strip used during the failed attempt. 2. Insert a new On Call Extra Test Strip. 3. Wait for the sample-ready indication. 4. Only then apply blood to the sample tip. For the complete testing procedure, read: [**How to Use On Call Extra Glucometer & Test Strips →**](/blogs/knowledge-hub/how-to-use-on-call-extra-glucometer-test-strips) * * * ## On Call Extra E4 Error – Used or Contaminated Test Strip **E-4** indicates that the meter has detected a strip that is already used, contaminated or otherwise unsuitable for testing. ### What to do for E4 Discard the affected strip and repeat the test using a **new compatible On Call Extra Test Strip**. Do not: - reuse a previously tested strip, - clean and reinsert a used strip, - use a visibly damaged strip, - use a strip from an opened damaged foil pouch, or - use a strip that may have been contaminated. If unused strips repeatedly produce E-4, check: - expiry, - storage conditions, - packaging integrity, - strip compatibility, and - whether the strip is being inserted correctly. For storage guidance: [**On Call Extra Test Strips Expiry & Storage Guide →**](/blogs/knowledge-hub/on-call-extra-test-strips-expiry-storage-guide) * * * ## On Call Extra E5 Error – Insufficient Sample or Late Re-Dosing **E-5** is particularly important on On Call Extra because it can relate to either an insufficient blood sample or an error caused by **late sample re-dosing**. The Extra system requires approximately **0.4 µL of fresh capillary whole blood**. ### If the first blood drop is insufficient When blood has been applied but the meter has not started its countdown, On Call Extra permits a second blood application within the manufacturer's short re-dosing window. The second sample should be applied within approximately **3 seconds**. ### Do not keep adding blood after the test has started If the meter has already begun its countdown and the check window is not properly filled, do not continue adding blood. Doing so can produce an E-5 message or potentially interfere with the test. Discard the strip and begin again with a new one according to the manufacturer's instructions. Read the dedicated guide: [**On Call Extra Re-Dosing & Second Blood Sample Guide →**](/blogs/knowledge-hub/on-call-extra-redosing-second-blood-sample-guide) * * * ## On Call Extra E6 Error – Battery Too Low **E-6** means the battery is too depleted for the meter to perform another glucose test. Replace the battery before continuing. The standard On Call Extra meter uses a **CR2032 3V coin-cell battery**. ### After replacing the battery - check that the battery is installed with the correct polarity, - close the battery cover securely, - check the date and time if necessary, and - repeat testing with a fresh strip. * * * ## Low-Battery Symbol vs E6 The low-battery symbol can appear while the meter still has enough power for a limited number of additional tests. The battery should nevertheless be replaced promptly. Once **E-6** appears, the battery is too low to continue glucose testing and should be replaced before another test is attempted. * * * ## On Call Extra E8 Error – Meter Electronics Failure **E-8** indicates an internal meter electronics failure. If E-8 persists after an appropriate restart, do not keep consuming additional test strips in an attempt to resolve the problem. Contact the supplier, distributor or appropriate product-support channel for further assistance. * * * ## On Call Extra E9 Error – Wrong or Damaged Test Strip **E-9** can appear when: - a strip other than an On Call Extra Test Strip is inserted, - the strip is damaged, or - the meter detects a strip calibration problem. ### How to troubleshoot E9 1. Remove the strip. 2. Confirm that the packaging specifically says **On Call Extra**. 3. Inspect the strip for visible damage. 4. Insert a new compatible Extra strip. 5. Repeat the test. If E-9 persists with genuine compatible undamaged strips, stop repeatedly testing and obtain product support. For model matching: [**On Call Extra Test Strip Compatibility Guide →**](/blogs/knowledge-hub/on-call-extra-test-strips-compatibility-guide) * * * ## On Call Extra E10 – Data Communication Failure **E-10** relates to a problem transferring stored meter data through an applicable data-management connection. This is a **data-transfer error rather than a blood-sample error**. Check the applicable cable, computer connection and On Call Diabetes Management Software instructions for the system being used. If you do not use the data-transfer function, this code will normally not be relevant to routine glucose testing. * * * ## On Call Extra E12 – Data Cable Connected During Test Mode **E-12** can appear when the meter's data-transfer cable is connected while: - a test strip is already inserted, and - the meter is waiting for blood-sample application. ### How to fix E12 1. Disconnect the data-transfer cable. 2. Remove the test strip. 3. Reinsert an appropriate strip to restart the test sequence. Follow the data-transfer instructions supplied with your meter/software if the problem continues. * * * ## On Call Extra HI – What Does It Mean? The standard On Call Extra measurement range is approximately **10–600 mg/dL**. A **HI** message indicates that the measured glucose concentration is above the meter's reportable range, greater than approximately **600 mg/dL**. This is not the same as an ordinary meter error. ### What to do if the meter displays HI 1. Check that your hands are clean and dry. 2. Repeat the test correctly with a fresh compatible strip to rule out a testing error. 3. If HI is repeated, seek prompt medical advice. A repeatedly confirmed HI reading may indicate extremely high blood glucose and should not be ignored. * * * ## On Call Extra LO – What Does It Mean? A **LO** message indicates that the measured glucose concentration is below the meter's approximately **10 mg/dL** lower reportable limit. If it is safe to do so without delaying necessary treatment, follow the meter's instructions for confirming the result with a fresh strip. A repeated LO reading or severe symptoms of low blood glucose require immediate attention according to the emergency plan provided by your healthcare professional. Seek urgent medical assistance when appropriate. * * * ## HI and LO Are Different from Temperature Warnings Do not confuse glucose-range messages with meter-temperature messages. Message Meaning **HI** Glucose concentration above the meter's measurable range **LO** Glucose concentration below the meter's measurable range **High-temperature warning** Meter/system is above the permitted operating temperature **Low-temperature warning** Meter/system is below the permitted operating temperature A temperature warning describes the testing environment or meter condition, not the person's glucose result. * * * ## On Call Extra Meter Too Hot If the system displays a high-temperature warning, move the meter to a cooler environment within the permitted operating range and allow it to stabilise before retesting. Do not rapidly cool the meter in a refrigerator, freezer or against ice. * * * ## On Call Extra Meter Too Cold If a low-temperature warning appears, move the meter to a warmer suitable environment and allow it to reach an appropriate operating temperature. If the meter has been stored in very cold conditions and will not switch on, the troubleshooting instructions advise allowing it approximately **30 minutes to reach room temperature** before trying again. * * * ## On Call Extra Meter Will Not Turn On If the meter is completely unresponsive, check the following before assuming that the device has failed. ### 1\. Check the battery The battery may be depleted, damaged or incorrectly installed. - Remove and reinstall it correctly. - Check battery polarity. - Replace it with a new compatible battery if necessary. ### 2\. Consider the temperature If the meter has been exposed to cold conditions, allow it approximately 30 minutes to reach room temperature and then retry. ### 3\. Insert a strip correctly A correctly inserted new On Call Extra strip normally activates test mode. If the strip is incorrectly inserted, the meter may not switch into the expected testing sequence. ### 4\. Persistent failure If the meter remains unresponsive after the battery and temperature have been checked, seek product support instead of repeatedly using additional strips. * * * ## On Call Extra Meter Is Not Reading the Test Strip If a strip is inserted but the meter does not recognise it, check: 1. **Meter model:** confirm the meter is On Call Extra. 2. **Strip family:** use On Call Extra Test Strips. 3. **Orientation:** insert the contact-bar end correctly. 4. **Insertion:** make sure the strip is fully seated. 5. **Condition:** use a new undamaged strip. 6. **Expiry:** check the printed manufacturer expiry. 7. **Storage:** confirm strips were stored correctly. 8. **Battery:** check that the meter has adequate power. If **E-9** appears, wrong-strip compatibility or strip damage should be checked first. * * * ## On Call Extra Recognises the Strip but the Countdown Does Not Start If the strip is recognised but the meter does not begin counting down after blood is applied, possible causes include: - insufficient sample volume, - blood applied to the wrong part of the strip, - blood applied too early, - incorrect strip family, - damaged or contaminated strip, or - incomplete filling of the strip check window. If the first application is insufficient and the countdown has not started, follow the Extra-specific re-dosing instructions. [**Read the On Call Extra Re-Dosing Guide →**](/blogs/knowledge-hub/on-call-extra-redosing-second-blood-sample-guide) * * * ## When Can I Apply a Second Blood Drop? The On Call Extra system permits a second blood application within approximately **3 seconds** when the initial application is insufficient and the meter has not yet begun its normal countdown. Do not treat this as unlimited re-dosing. If the meter has already started counting down or the permitted window has passed, follow the manufacturer instructions and use a new strip where required. * * * ## Why Does On Call Extra Keep Showing E5? Repeated E-5 messages may indicate a recurring sample-application problem. Check: - whether the blood drop is large enough, - whether blood is being applied to the sample tip, - whether the check window fills correctly, - whether re-dosing is taking place within the permitted window, - whether the strip is new and undamaged, and - whether you are using compatible On Call Extra strips. For the complete testing procedure: [**How to Use On Call Extra Glucometer & Test Strips →**](/blogs/knowledge-hub/how-to-use-on-call-extra-glucometer-test-strips) * * * ## Unexpected On Call Extra Results – What Should You Check? An unexpected result does not automatically mean that the meter is defective. Check: - hand washing and drying, - strip compatibility, - strip expiry, - strip storage, - correct sample application, - adequate blood volume, - meter operating temperature, and - whether a control solution test is appropriate. If an unexpected result remains high or low after correct repeat testing, seek professional medical advice rather than changing treatment solely on the basis of troubleshooting. * * * ## When Should You Perform a Control Solution Test? A control solution test can help confirm that the meter and test-strip system are working together as expected. Follow the manufacturer instructions for control testing, particularly when: - you are checking a new meter, - you are concerned about strip condition or storage, - the meter has been dropped or damaged, - results repeatedly appear unexpected, or - you want to verify the meter-and-strip testing system. Control solution is not blood, and the displayed control result should not be interpreted as a personal glucose measurement. * * * ## How to Reduce On Call Extra Testing Errors - Use only compatible On Call Extra Test Strips. - Check expiry before testing. - Store strips according to manufacturer instructions. - Keep foil-packed strips sealed until use. - Close vial-packed strips promptly where applicable. - Wait for the sample-ready symbol before applying blood. - Use an adequate sample. - Apply blood to the correct sample tip. - Use the re-dosing feature only within the specified window. - Keep the strip in place during testing. - Replace a weak battery promptly. - Do not test outside the permitted operating conditions. * * * ## On Call Extra vs On Call Plus Error Codes Do not automatically use On Call Plus troubleshooting instructions for an **On Call Extra** meter. Although several error concepts look similar, the systems differ in their strip technology, coding method, sample requirement and re-dosing behaviour. If your meter says On Call Plus, use: [**On Call Plus Error Codes & Troubleshooting Guide →**](/blogs/knowledge-hub/on-call-plus-error-codes-troubleshooting-guide) For a system comparison: [**On Call Plus vs On Call Extra Glucometer →**](/blogs/knowledge-hub/on-call-plus-vs-on-call-extra-glucometer) * * * ## Need Compatible On Call Extra Test Strips? Troubleshooting cannot correct a genuine compatibility problem if the wrong strip family is being used. - [**On Call Extra Test Strips 50 →**](/products/oncall-extra-glucometer-strips) - [**On Call Extra Test Strips 100 →**](/products/oncall-extra-glucometer-strips-100) - [**On Call Extra Individually Foil-Packed Test Strips →**](/products/on-call-extra-glucometer-foiled-test-strips) Compare the available formats: [**On Call Extra 50 vs 100 vs Foil Pack Guide →**](/blogs/knowledge-hub/on-call-extra-strips-50-vs-100-vs-foil-pack) * * * ## Frequently Asked Questions ### What does E0 mean on On Call Extra? E-0 indicates a power-on self-check error. Remove the battery for approximately 30 seconds, reinstall it and restart the meter. Seek support if the error continues. ### What does E1 mean on On Call Extra? E-1 indicates an internal calibration-check error. Turn the meter off or remove the strip, then restart and repeat testing with a fresh strip. ### What does E2 mean on On Call Extra? E-2 means the test strip was removed during testing. Repeat with a new strip and leave it fully inserted until the test is finished. ### What does E3 mean on On Call Extra? E-3 means the sample was applied before the meter was ready. Use a new strip and wait for the blood-drop / strip-ready symbol before applying blood. ### What does E4 mean on On Call Extra? E-4 indicates that the strip may already be used, contaminated or unsuitable. Discard it and repeat with a new compatible Extra strip. ### What does E5 mean on On Call Extra? E-5 can indicate insufficient sample or a sample-application problem caused by late re-dosing. Apply enough blood correctly and use the manufacturer's approximately 3-second re-dosing window only where appropriate. ### What does E6 mean on On Call Extra? E-6 means the battery is too depleted to perform another glucose test. Replace the battery before retesting. ### What does E8 mean on On Call Extra? E-8 indicates an internal meter electronics failure. If it persists, stop repeated testing and obtain technical support. ### What does E9 mean on On Call Extra? E-9 can indicate that the wrong type of test strip has been inserted or that the strip is damaged or has a calibration problem. Confirm On Call Extra compatibility and retry with a new strip. ### What does HI mean on On Call Extra? HI means the measured glucose concentration is above the meter's approximately 600 mg/dL upper reportable limit. Repeat testing according to the manufacturer instructions and seek prompt medical advice if HI is confirmed. ### What does LO mean on On Call Extra? LO means the measured glucose concentration is below the meter's approximately 10 mg/dL lower reportable limit. A repeated LO result can represent severe low blood glucose and requires appropriate immediate action according to medical guidance. ### Why does my On Call Extra meter not recognise the strip? Check that the strip is genuinely intended for On Call Extra, correctly inserted, new, undamaged, within expiry and properly stored. Also check meter battery condition. ### Can I add more blood if the first sample is too small? On Call Extra permits a second sample application within approximately 3 seconds under the manufacturer's specified conditions. Do not continue adding blood once the permitted window has passed or the meter has progressed through the test. * * * ## Related On Call Extra Guides - [On Call Extra Glucometer & Test Strips Complete Guide](/blogs/knowledge-hub/on-call-extra-glucometer-test-strips-complete-guide) - [On Call Extra Test Strip Compatibility Guide](/blogs/knowledge-hub/on-call-extra-test-strips-compatibility-guide) - [How to Use On Call Extra Glucometer & Test Strips](/blogs/knowledge-hub/how-to-use-on-call-extra-glucometer-test-strips) - [On Call Extra Re-Dosing & Second Blood Sample Guide](/blogs/knowledge-hub/on-call-extra-redosing-second-blood-sample-guide) - [On Call Extra Test Strips Expiry & Storage Guide](/blogs/knowledge-hub/on-call-extra-test-strips-expiry-storage-guide) - [On Call Extra Test Strips 50 vs 100 vs Foil Pack](/blogs/knowledge-hub/on-call-extra-strips-50-vs-100-vs-foil-pack) - [On Call Plus vs On Call Extra Glucometer Comparison](/blogs/knowledge-hub/on-call-plus-vs-on-call-extra-glucometer) - [On Call Plus, Extra & GK Dual Complete Guide](/blogs/knowledge-hub/on-call-glucometers-test-strips-complete-guide) - [General Glucometer Setup, Error Codes & Troubleshooting Guide](/blogs/knowledge-hub/glucometer-setup-use-error-codes-troubleshooting) * * * ## Shop On Call Extra at Microsidd - [**On Call Extra Glucometer Kit**](/products/oncall-extra-glucometer) - [**On Call Extra Test Strips 50**](/products/oncall-extra-glucometer-strips) - [**On Call Extra Test Strips 100**](/products/oncall-extra-glucometer-strips-100) View the complete range: [**Shop On Call Extra Glucometers & Test Strips →**](/collections/on-call-extra-glucometer-strips) * * * **Medical information notice:** This troubleshooting guide explains meter messages and general operation of the On Call Extra blood glucose monitoring system. It does not diagnose a medical condition, determine whether an individual glucose result is clinically safe or replace the instructions supplied with your exact meter and strips. If a glucose result is unexpectedly high or low, follow the manufacturer's instructions for repeat testing where appropriate. Do not change medication, insulin dosage or other treatment solely on the basis of this troubleshooting article. Repeated **HI or LO results, severe symptoms, confusion, loss of consciousness or inability to self-treat require prompt medical assessment**. Do not delay appropriate medical care while troubleshooting the meter. **Tags:** How to Use On Call Plus Glucometer & Test Strips: Step-by-Step Guide, MicroSidd On Call Extra, On Call Extra Error Codes & Troubleshooting Guide, On Call Extra Glucometer & Test Strips Complete Guide, On Call Plus vs On Call Extra glucometer and test strips comparison, On-Call Extra Glucometer, On-Call Extra Glucometer Strips --- > Source: [Microsidd India](https://microsidd.com/blogs/knowledge-hub/on-call-extra-error-codes-troubleshooting-guide)