Error with a number on a pulse oximeter (Error 3, 4, 6, 7)
The oximeter has found a fault in its own parts — a light source, the light sensor or the screen — and will not measure. Unlike Finger Out or dashes, this is about the device, not about your finger or the signal.
Check your oximeter’s manual — makers differ.
What it is for
Look the number up in your own manual or in the tables below for the models read. For these codes neither maker gives a fix you can do yourself; both point to their service: Beurer says to “Contact the retailer or Customer Services”, and Microlife says to check the light or contact Microlife customer service.
These pages report what each maker’s manual says and quote it wherever health is involved. They do not diagnose anything, they are not medical advice, and they do not tell you whether an oxygen or pulse reading is right for you or what to do about it; only your own oximeter’s manual and your doctor or nurse can do that for the person you are looking after.
- What it looks like
- The word Error followed by a single digit, in place of the readings.
- Names makers use
- «Error 3», «Error 4», «Error 6», «Error 7» (Microlife OXY 300); “Error 3”, “Error 4”, “Error 6”, “Error 7” (Beurer PO 45)
Where makes differ
The Beurer PO 45 and the Microlife OXY 300 give Error 3, 4, 6 and 7 the same meanings, but that does not make the codes universal: other models and makers may use other numbers. Nonin’s 9590 and Masimo’s MightySat list no numbered error codes in the manuals read; Masimo’s troubleshooting table goes by what you see instead.
The codes, maker by maker
| Code | What it means | What to do |
|---|---|---|
| Error 3 | “The red emission LED is damaged.” | “Check the red emission LED.” |
| Error 4 | “The infrared emission LED is damaged.” | “Check the infrared emission LED.” |
| Error 6 | “The screen has failed.” | “Contact your local Microlife-Customer Service.” |
| Error 7 | “The emission LED or reception diode is damaged.” | “Contact your local Microlife-Customer Service.” |
| Code | What it means | What to do |
|---|---|---|
| Error 3 | “The red light receiving LED is faulty” | “Contact the retailer or Customer Services” |
| Error 4 | “The infrared light receiving LED is faulty” | “Contact the retailer or Customer Services” |
| Error 6 | “The display is faulty.” | “Contact the retailer or Customer Services” |
| Error 7 | “The receiving LEDs are faulty” | “Contact the retailer or Customer Services” |
What it does not mean
An error code is not a reading and says nothing about your oxygen or pulse. It is not Finger Out, which only means the finger is not detected.
Other symbols with the same shapes
Sources
No published standard we could check defines what a fingertip pulse oximeter’s display shows, so this meaning is taken from 2 makers’ own manuals and support pages, each fetched and read on the date shown:
- Microlife: Microlife OXY 300 fingertip pulse oximeter — instruction manual (IB OXY 300 N-V9, revision 2023-11-30, PDF) — Malfunctions and actions to take: «Error 3» red emission LED damaged, «Error 4» infrared emission LED damaged, «Error 6» screen failed, «Error 7» emission LED or reception diode damaged. Checked 2026-09-29.
- Beurer: Beurer PO 45 pulse oximeter — instructions for use (2020-06-12, German/English, PDF linked from beurer.com) — What if there are problems?: “Error 3”, “Error 4”, “Error 6” and “Error 7” appear on the display, each with its cause and “Contact the retailer or Customer Services”. Checked 2026-09-29.
Written in our own words; quotations are the makers’ wording.