An “E2” on a blood pressure monitor is an error code telling you the device could not complete or trust the measurement it just attempted. On most home monitors, E2 specifically flags that something disrupted the pressure signal inside the cuff, usually arm movement, muscle tensing, or an unstable pulse pattern. The code does not mean your blood pressure is dangerously high or low; it means the machine’s sensors picked up noise they could not interpret. The fix is almost always a simple adjustment to how you are sitting, how the cuff is placed, or how still you are holding your arm, though in some cases a persistent E2 points to something worth mentioning to your doctor.
Why Blood Pressure Monitors Throw Errors in the First Place
Home blood pressure monitors are oscillometric devices, meaning they do not listen for pulse sounds the way a doctor does with a stethoscope. Instead, the monitor inflates a cuff until it blocks blood flow, then slowly deflates while a tiny pressure sensor watches for rhythmic fluctuations caused by each heartbeat pushing against the cuff. The machine records a pattern of pulse waves that start out flat, grow to a peak, and then diminish as the cuff loosens. It uses that wave pattern plus a built-in algorithm to estimate your systolic and diastolic numbers.1Journal of Human Hypertension. Oscillometric measurement of blood pressure: a simplified explanation
This process is sensitive. The sensor is trying to detect pressure changes of just a few millimeters of mercury riding on top of a cuff pressure that may be above 200 mmHg. Anything that introduces extra pressure fluctuations, whether it is your arm shifting, your fingers clenching, or your heart skipping a beat, can make the signal unreadable. When the algorithm cannot extract a clean wave pattern, it aborts the reading and displays an error code rather than giving you a number it does not trust. One study in an emergency department setting found that about 31% of inflationary-mode blood pressure measurements failed, primarily because of arrhythmia or body movement.2PubMed Central. Validation of inflationary noninvasive blood pressure monitoring in the emergency room Home monitors are similarly vulnerable to these disruptions.
What Specifically Triggers E2
Error code labels are not universal across every brand. Omron, one of the most widely sold home monitor brands, uses E2 to mean the device detected an abnormal pressure change during measurement, almost always caused by movement. Other manufacturers, including Beurer, A&D, and Withings, may assign different meanings to the same alphanumeric code, or use different codes entirely for the same problem. Your user manual is the definitive reference for your specific device. That said, the vast majority of E2 errors across the most popular monitors share a common set of root causes.
- Arm or body movement: Even subtle motions like adjusting your posture, turning your head, or shifting your weight can inject enough noise into the cuff signal to corrupt the reading.
- Talking or coughing: Speaking engages your diaphragm and chest muscles, which changes the pressure in your torso and can affect blood flow to the arm enough to disrupt the signal.
- Muscle tension: Gripping the armrest, clenching your fist, or tensing your forearm muscles changes the volume of your limb inside the cuff and distorts the oscillometric wave.
- Loose or shifting cuff: If the cuff is not snug, it can slide during inflation, changing its relationship to the artery and garbling the pressure data.
- Irregular heartbeat: Some monitors will display E2 or a related error when the pulse pattern is too erratic to analyze. Others have a separate irregular heartbeat indicator.
The common thread is that the monitor needs a clean, repeating waveform to do its math, and anything that breaks that pattern forces it to give up.
The Cuff Matters More Than You Think
A poorly fitting cuff does not just produce inaccurate readings; it can prevent the monitor from completing a reading at all. If the cuff is too loose, the sensor cannot detect enough of the arterial pulsation to build a usable wave pattern. If the cuff slides during inflation because it was not secured properly, the sudden change in contact area looks like movement to the algorithm, and you get an error code.
Cuff size also plays a role in accuracy even when the measurement does complete. A randomized crossover trial found that using a regular-sized cuff on someone who needed an extra-large cuff inflated the systolic reading by about 19.5 mmHg, while using a regular cuff on someone who needed a small cuff pushed the reading about 3.6 mmHg too low.3JAMA Internal Medicine. Effects of Cuff Size on the Accuracy of Blood Pressure Readings: The Cuff(SZ) Randomized Crossover Trial Those are large enough errors to change a diagnosis. If your arm circumference is near the boundary of your cuff’s range, you may be getting both errors and inaccurate readings, and switching to the correct cuff size can solve both problems at once.
Most monitors ship with a cuff designed for arm circumferences of roughly 22 to 42 cm. If your arm is larger, you likely need a large or extra-large cuff sold separately. The cuff’s bladder should wrap around at least 80% of your upper arm. When you tighten it, you should be able to fit one finger underneath but not two.
How Your Position Affects the Reading
Your body position during measurement has a surprisingly large effect on the numbers the monitor produces, and certain positions also make errors more likely. The standard recommendation from the American Heart Association is to sit with your back supported, feet flat on the floor, and the cuffed arm resting on a surface at heart level. A trial comparing routine clinical measurement (often taken with the patient sitting on an exam table, feet dangling, arm unsupported) to AHA-recommended positioning found that proper positioning produced substantially lower readings, enough to reclassify some patients from hypertensive to normal.4PubMed Central. Comparison of outcomes for routine versus American Heart Association-recommended technique for blood pressure measurement (CORRECT BP): a randomised cohort study
When your arm is unsupported, the muscles in your arm and shoulder engage to hold it in place, and that muscle tension is exactly the kind of noise that can trigger an E2 error. Sitting on a bed with your legs stretched out, standing, or crossing your legs can also change the readings and increase the chance of a failed measurement. Research comparing positions found that systolic blood pressure was highest when lying flat and tended to drop in a standing position, with statistically meaningful differences across positions.5PubMed. The effect of different body positions on blood pressure The point for error avoidance is consistency: pick a stable, supported seated position, and use the same one every time.
The five-minute rest period before measuring that you see recommended in many guidelines also matters, though perhaps less than you would expect. A study of postpartum women doing home monitoring found that readings taken after a full five-minute seated rest were only about 1.2 mmHg lower systolically than readings taken without the rest period.6PubMed Central. Compliance and Impact of a 5-Min Seated Rest Protocol on Home Blood Pressure Monitoring in Postpartum Women The rest period is still a good idea because it also reduces the chance that residual movement and elevated heart rate from walking over to the monitor will trip an error.
Irregular Heartbeat and E2
Some monitors conflate irregular heartbeat detection with their general error code, while others use a separate heart symbol or “IHB” indicator. If you keep getting E2 without obvious movement or cuff issues, an irregular heart rhythm could be the culprit. Atrial fibrillation, premature ventricular contractions, and other arrhythmias create uneven pulse waves that make it difficult for the oscillometric algorithm to identify the peak of the waveform. The machine may interpret the irregular pattern as noise and refuse to produce a number.
Modern monitors are getting better at handling this. Some devices now include algorithms specifically designed to detect atrial fibrillation, and these can distinguish an arrhythmia-related irregular signal from a movement-related one. One study of an automated monitor with an irregular heartbeat algorithm found that it correctly identified atrial fibrillation with about 97% sensitivity and 96% specificity when using a three-measurement protocol.7PubMed Central. Diagnostic Performance of an Automated Blood Pressure Monitor With an Irregular Heartbeat Algorithm Designed to Detect Atrial Fibrillation If your monitor does have this feature and flags an irregular heartbeat alongside or instead of E2, that is worth bringing to your doctor’s attention, especially if it happens repeatedly.
If you have a known arrhythmia and your oscillometric monitor throws constant errors, you may need to measure using a manual sphygmomanometer and stethoscope, or ask your doctor about ambulatory monitoring. Oscillometric devices fundamentally depend on a repeating pulse pattern, and a chaotic rhythm can make that impossible regardless of how still you sit.
Wrist Monitors and Their Extra Challenges
Wrist blood pressure monitors are more convenient but also more prone to errors, including E2. The radial artery at the wrist is smaller and sits closer to the bone than the brachial artery in the upper arm, so the oscillometric signal is weaker and more easily disrupted. Wrist monitors are also extremely sensitive to hand position. If your wrist is even a few inches above or below heart level, the hydrostatic pressure difference changes the reading meaningfully.
Research on wrist-level measurements found that when the hand was held about 25 cm below the heart, systolic blood pressure readings carried an average error of roughly 13.5 mmHg. Raising the hand 25 cm above the heart still produced errors around 9.6 mmHg.8Nature / npj Biosensors. A method for blood pressure hydrostatic pressure correction using wearable inertial sensors and deep learning These are large enough errors that the monitor may sometimes reject the reading outright and show an error code instead of displaying a dubious number. If you use a wrist monitor, hold your wrist at heart level, usually by placing your elbow on a table and bringing your wrist up in front of your chest. Even small deviations make a difference.
Step-by-Step Troubleshooting for E2
When your monitor shows E2, try these steps before assuming something is wrong with the device or with you.
- Wait two to three minutes: Give your arm a break so blood flow normalizes. Immediately retaking tends to produce another error or an artificially elevated reading because the cuff just compressed your artery.
- Check the cuff: Make sure it is snug (one finger fits underneath), positioned on bare skin or a thin layer, and centered over the brachial artery on the inner part of your upper arm. Most cuffs have an artery marker printed on them.
- Sit properly: Back against the chair, feet flat on the floor, cuffed arm on a table so the cuff sits at heart level. Uncross your legs.
- Stay still and quiet: Do not talk, adjust the cuff, or move once you press start. Keep your hand open and relaxed, not clenched.
- Try the other arm: If you suspect the cuff is not sitting well on one arm, switching can help. Blood pressure naturally differs a bit between arms, but the monitor should at least complete the reading.
- Replace the batteries: Low battery power can cause the pump and sensor to underperform, leading to incomplete measurements and error codes. Fresh batteries are an easy fix to rule out.
If you follow all of these steps and still get E2 on three consecutive attempts, the issue is less likely to be technique. At that point, either the device itself has a problem, or something physiological, like an arrhythmia, is interfering with the measurement.
Other Common Error Codes and What They Mean
Monitors typically display a handful of different error codes, each pointing to a different problem. While the exact labeling varies by brand, the general pattern across most popular home devices looks like this:
- E1 (or Er 1): The cuff did not detect enough signal to even begin. Usually means the cuff is too loose, not plugged in, or the tube is kinked.
- E3 (or Er 3): The device could not inflate the cuff to the necessary pressure, or inflation took too long. Often caused by a leak in the cuff or tubing, or by an arm that is too large for the cuff.
- E5 or EE: On some monitors, this indicates an abnormally high or low reading that the device considers potentially unreliable. It is not always an error per se, but a flag that the result may not be trustworthy.
- Heart or IHB symbol: An irregular heartbeat was detected. The reading may or may not still be displayed alongside this symbol, depending on the model.
If your monitor shows an error code not listed here, check the manual that came with the device. Manufacturer websites also typically list their codes on a troubleshooting page. The codes matter because they tell you where to focus your fix: E1 is almost always a cuff connection problem, E2 is almost always a signal disruption, and E3 is almost always a hardware or fit issue.
When Repeated Errors Are Worth a Doctor Visit
An occasional E2 is completely normal and usually just means you moved. But if you consistently cannot get a reading despite following proper technique, there are a few things to consider. First, an undiagnosed arrhythmia may be making oscillometric measurement unreliable for you. Atrial fibrillation affects a growing number of adults, and many people do not know they have it until something like a persistent blood pressure monitor error brings it to attention. As noted above, newer monitors with dedicated irregular heartbeat algorithms can flag this possibility.
Second, some vascular conditions, like significant arterial stiffness or peripheral artery disease, can alter the oscillometric waveform enough to cause frequent measurement failures. These conditions change how the pulse wave travels through the arm, and the monitor’s algorithm may not be calibrated to handle the unusual pattern. If you have diabetes, kidney disease, or other conditions that affect blood vessels, mention repeated monitor errors to your doctor.
Third, if you are pregnant, be aware that blood pressure monitors in general are less reliable during pregnancy. A systematic review found that only about a third of devices tested in pregnant women passed their validation protocol without violations.9PubMed Central. Accuracy of Blood Pressure Measurement Devices in Pregnancy: A Systematic Review of Validation Studies Hemodynamic changes in pregnancy alter blood flow patterns enough to affect oscillometric accuracy. If you are monitoring blood pressure during pregnancy and getting frequent errors, your provider may recommend a specific validated device. Studies are ongoing to validate more monitors specifically for this population.10PubMed Central. Clinical Accuracy of the G.LAB MD41A0 Upper Arm Blood Pressure Monitor in Pregnancy and Pre-Eclampsia Using the AAMI/ESH/ISO as Reference Standard
Choosing a Validated Monitor
Not all blood pressure monitors sold to consumers have been independently tested for accuracy. Over the past three decades, organizations including the Association for the Advancement of Medical Instrumentation, the European Society of Hypertension, and the International Organization for Standardization have developed protocols that set minimum accuracy standards for these devices.11PubMed Central. A universal standard for the validation of blood pressure measuring devices These protocols were eventually merged into a single universal standard to make it easier to compare devices.12PubMed Central. Validation protocols for blood pressure measuring devices in the 21st century
A validated monitor is not immune to E2 errors, but it is less likely to produce them unnecessarily. Cheaper unvalidated devices sometimes use less sophisticated algorithms that are quicker to give up when the signal is imperfect. The STRIDE BP website and the British and Irish Hypertension Society both maintain searchable lists of monitors that have passed independent validation testing. If you are shopping for a new monitor, checking one of those lists is the single most useful thing you can do. A validated upper-arm monitor with a properly sized cuff, used while sitting correctly, will give you reliable readings and far fewer frustrating error codes.