Nellcor N-600x — EE 718 Error: Diagnostic Steps
Covidien Nellcor N-600x · Error EE 718 · Updated May 4, 2026
The Nellcor N-600x pulse oximeter shows EE 718 when the unit detects an internal hardware fault during its self-test. Unlike alarms tied to a patient sensor (motion, low perfusion), an EE-series code points the technician at the device itself — the meter will refuse to take measurements until the fault is cleared.
What the error means
EE 718 is in the family of internal hardware error codes the N-600x raises when a startup or runtime self-test fails. The unit may or may not retain the error after a power cycle. If it clears after a reboot and never returns, the original cause was likely transient. If it returns immediately or under load, the unit needs servicing.
Common causes
- A damaged or bent sensor connector (DOC-10) seating poorly in the unit
- A failing internal battery — voltage drops below threshold during self-test
- A loose ribbon cable inside the unit after a recent drop
- Liquid ingress around the sensor port, common in transport use
- An aged main board reaching the end of its service life
Diagnostic steps
1. Disconnect the patient sensor and the DOC-10 extension cable. Power-cycle the monitor with mains power only. 2. If EE 718 returns with no sensor attached, the fault is internal — skip to step 6. 3. Reconnect the DOC-10 alone (no SpO2 sensor). If the error returns, the DOC-10 cable or its connector is suspect — substitute a known-good cable. 4. Reconnect a known-good adult finger sensor. If the error returns only with a sensor attached, replace the sensor. 5. Inspect the sensor port on the front of the unit under good light. Bent pins, debris, or visible corrosion warrant a port replacement. 6. Run on AC mains only with the battery removed. If the error clears, the battery is failing under load — replace it. 7. If the error persists with no battery, no sensor, and no extension cable, the unit needs a board-level service. Document and remove from service.
When to escalate
If steps 1–6 do not clear the error, do not return the unit to service. Pulse oximetry is a critical-care reading and an unresolved EE-class fault means the unit cannot guarantee accurate measurements. Send it to the manufacturer or an authorised service centre — the main board is not a field-replaceable part on this generation.
Related errors
- EE 719 / EE 720 — adjacent codes in the same hardware-fault family; similar diagnostic flow applies. - Sensor Off — sensor-side problem, not internal. - Pulse Search — perfusion or placement, not a hardware fault.