Defibrillators · E Series family

ZOLL E: troubleshooting and error codes

The ServiceForge knowledge base holds 17 documented symptoms for the ZOLL E, with 54 ranked causes, 49 diagnostic checks with test points and expected values, and 128 error codes. Each symptom below shows its causes and the first check; the rest is one connection away. Connect ServiceForge to your AI

Symptoms

Displayed heart rate not accurate (artifact present) patient safety

Heart rate display inaccurate with ECG artifact visible, signal contamination from movement or interference

Ranked causes

1. ECG cable or electrode movement causing artifact (common)
2. Patient movement or muscle artifact (common)
3. Excessive radio frequency interference (RFI) (occasional)
4. Poor electrode-to-patient connection (common)
5. ECG cable connectivity issue (occasional)
6. Contamination on electrode snaps or broken springs (occasional)
7. Intermittent ECG patient cable or connector wiring (occasional)
8. Defective ECG input connector (rare)
9. Faulty ECG connector-to-system board cable (rare)
10. Defective system board (rare)

First check

Inspect ECG cable routing and electrode connections

Test point: ECG cable path and electrode attachment
Expected: Cables routed away from movement, electrodes secure

6 more checks with pass and fail actions, 10 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Flash or arcing under defibrillator pad patient safety

Electrical arcing or flashing visible under defibrillator pad during pad application or operation, risk of skin burn

Ranked causes

1. Increased skin conductivity from alcohol or betadine preparation (common)
2. Gel leakage from pad (gel droop) (common)
3. Poor pad coupling to patient's skin (common)
4. Dried out gel on defibrillator pad (common)
5. Excessive patient hair (common)
6. Expired defibrillator pads (occasional)
7. Chest compression applied through pads (occasional)
8. Front pad placed before back pad positioning (occasional)
9. Wet gel pads stored improperly (occasional)

First check

Verify skin preparation method

Test point: Patient skin preparation method
Expected: No alcohol or betadine used

5 more checks with pass and fail actions, 9 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

ECG LEAD OFF message displays patient safety

Monitor shows ECG LEAD OFF message for 3, 5, or 12-lead cable, indicating loss of signal from electrodes or cable connection issue

Ranked causes

1. Poor electrode contact due to skin preparation or dry gel (common)
2. Expired ECG electrodes (occasional)
3. Loose or disconnected ECG leads (common)
4. ECG cable corrosion, broken connector pins, or intermittent connections (occasional)
5. Faulty ECG input connector or pins (occasional)
6. Defective ECG cable connection to system board (occasional)
7. Damaged or degraded system board ECG shielding (rare)
8. Defective system board (rare)

First check

Verify electrode site preparation and gel condition

Test point: Electrode contact area on patient skin
Expected: Site clean, skin lightly abraded, gel moist

6 more checks with pass and fail actions, 8 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

CHECK PADS/POOR PAD CONTACT message displays patient safety

Monitor displays CHECK PADS or POOR PAD CONTACT message indicating defibrillator pad connectivity or condition issue

Ranked causes

1. Loose or improperly inserted PADS connector (common)
2. Damaged defibrillator pads, wires, or connector (common)
3. Dried out or expired defibrillator pads (common)
4. Poor pad skin contact due to hair or moisture (common)
5. Universal cable shorted or open circuit (occasional)
6. Faulty High Voltage Module (occasional)
7. Defective system board (rare)

First check

Verify PADS connector is properly seated in cable

Test point: PADS connector to universal cable connection
Expected: Connector firmly inserted with no gaps

4 more checks with pass and fail actions, 7 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Displayed heart rate not accurate (no artifact) patient safety

Heart rate display on monitor does not match actual patient heart rate; no ECG artifact visible

Ranked causes

1. Incorrect lead selection (common)
2. Heart rate not flashing synchronously with QRS (common)
3. Non-optimal ECG waveform size (occasional)
4. Poorly positioned ECG electrodes (common)

First check

Verify heart rate flashes synchronously with QRS

Test point: Monitor ECG display
Expected: Heart rate indicator flashes with each QRS

3 more checks with pass and fail actions, 4 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

EtCO2 monitor not displaying waveform patient safety

CO2 waveform does not appear on display after warm-up and zeroing procedure

Ranked causes

1. CO2 cable not properly connected to yellow connector (common)
2. Monitor not in correct operating mode (occasional)
3. CO2 module not warmed up or zeroed (common)

First check

Verify CO2 cable connection to yellow connector

Test point: Yellow connector at back of E Series
Expected: CAPNOSTAT 5 cable connected with airway adapter or cannula installed

5 more checks with pass and fail actions, 3 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

NIBP calibration fails patient safety

E Series displays FAIL reading instead of PASS during low or high point calibration

Ranked causes

1. NIBP Analyzer pressure setting incorrect (common)
2. NIBP Analyzer connection to E Series loose or faulty (common)

2 corrective actions and part numbers are in ServiceForge. Connect ServiceForge to your AI

V LEADS OFF message displays patient safety

Monitor shows V LEADS OFF message indicating V lead connection failure or improper termination

Ranked causes

1. V lead terminator not attached to unused V lead connector (common)
2. V1 lead metal snap in contact with patient skin (occasional)

First check

Check if V leads are in use

Test point: V lead connector
Expected: Either V leads connected or terminator plug attached

1 more check with pass and fail actions, 2 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Calibration: Strip chart pulses

Verify calibration signal output on strip chart recorder and video display

Ranked causes

1. Calibration signal verification required (unknown)

First check

Press RECORDER button

Test point: RECORDER button
Expected: Recorder activated

1 more check with pass and fail actions are in ServiceForge. Connect ServiceForge to your AI

Electronic interference

Radio frequency interference (RFI) or other electronic noise affecting defibrillator operation

Ranked causes

1. Excessive radio frequency interference from nearby equipment (occasional)

First check

Identify and mitigate RFI sources

Test point: Surrounding electrical equipment
Expected: No strong RFI sources nearby or turned off

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

False "Pacer Pulses Seen" message patient safety

Defibrillator displays pacer pulse detection when patient does not have internal pacemaker

Ranked causes

1. High-frequency artifact triggering pacer detection (common)

First check

Disable pacer detection feature

Test point: Enable Pacer Detection setting
Expected: Feature disabled

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Low battery detection

Verify LOW BATTERY message displays and clears at correct voltage thresholds

Ranked causes

1. Low battery detection circuit malfunction (unknown)

First check

Verify no low battery alert at safe voltage

Test point: Battery well terminals
Expected: No LOW BATTERY message V

1 more check with pass and fail actions, 1 corrective action, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Off-mode leakage current test

Measure standby current draw when unit is powered off

Ranked causes

1. Excessive leakage current in OFF mode (unknown)

First check

Measure voltage across leakage current shunt resistor

Test point: 1kΩ resistor terminals
Expected: Less than 450 mV, < 450 mV
Tools: DMM set to DCV

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Power supply voltage threshold test high voltage

Verify unit power-on and power-off thresholds at specific voltage levels

Ranked causes

1. Power supply voltage out of specification (unknown)

First check

Verify unit does not power on at low voltage

Test point: Battery well terminals
Expected: Unit should not turn on

1 more check with pass and fail actions, 1 corrective action, and part numbers are in ServiceForge. Connect ServiceForge to your AI

System current (ON mode) test high voltage

Measure current draw when unit is powered on at nominal voltage

Ranked causes

1. Excessive current draw in ON mode (unknown)

First check

Measure voltage across current shunt resistor

Test point: 0.1Ω resistor terminals
Expected: 116 mV or less, ≤ 116 mV
Tools: Fluke 75 multimeter or equivalent

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Unit shutdown voltage test

Verify unit shuts down automatically at low voltage

Ranked causes

1. Shutdown circuit malfunction or incorrect threshold (unknown)

First check

Verify automatic shutdown at low voltage

Test point: Battery well terminals
Expected: Unit should shut off within 30 seconds V

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Wandering baseline patient safety

ECG baseline wanders or drifts on display, indicating signal quality issue similar to heart rate inaccuracy

Ranked causes

1. ECG signal quality issue (see Displayed HR not accurate) (common)

First check

Follow artifact removal procedures from HR inaccuracy troubleshooting

Test point: ECG cable and electrodes
Expected: Baseline stabilized

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Error codes

Code	Meaning	Trigger	Severity
`200J MAX BIPHASIC`	User attempted to set defibrillation energy >200J on Biphasic Unit	User tries to set energy above 200J limit	info
`ANALYSIS HALTED`	ECG analysis halted due to user interaction or charging error	Lead/size change, Analyze button pressed again, Impedance fault, or Charging error in auto defib mode	warning
`AUDIO FAULT 136`	Audio DSP hardware error	Audio DSP hardware malfunction	error
`AUDIO NOT RECORDING`	Audio is not recording	Recording system malfunction	error
`AUDIO QUEUE FULL`	Audio output queue is full	Too many voice prompts queued simultaneously	warning
`BATT HIGH CURRENT`	Battery current out of acceptable range	Battery charged with current >0.1A or battery not charged with current >1.6A	error
`BATT HIGH VOLTAGE`	Battery voltage exceeds safe limit	Battery voltage >15.5V	error
`BATT LOW CURRENT`	Battery current below acceptable range	Battery not charged with current <0.35A	error
`BATT LOW VOLTAGE`	Battery voltage insufficient for operation	Battery voltage <9.5V	error
`BATT OVERCHARGE`	Battery charger has been on too long	Charger remains on for >4 hours	error
`CABLE FAULT`	Incorrect A/D reading for paddle ID in auto defib mode	Paddle ID detection failure	error
`CARD FULL`	Memory card is full	Memory card storage capacity exceeded	warning
`CHECK CO2 ADAPTER`	Airway adapter is removed, occluded, or zeroing needs to be performed	Adapter missing/occluded or zeroing failed	unknown
`CHECK CO2 SENSOR`	EtCO2 Sensor is unplugged or defective	Sensor not detected or sensor failure	unknown
`CHECK PADS`	Defibrillation pads have poor contact or are shorted	POOR PAD CONTACT or DEFIB PAD SHORT message	unknown
`CHECK PADS`	Defibrillator pad connection or condition issue preventing proper pad function or testing	Loose pad connector, damaged pads or cable, dry/expired pads, poor pad-to-skin contact	error
`CHECK PATIENT`	Background ECG analysis detects shockable rhythm	Shockable rhythm detected on monitor	unknown
`CHECK PULSE`	Alternate message for NO SHOCK ADVISED	No shockable rhythm detected or after third shock	unknown
`CHECK RECORDER`	Paper recorder fault - paper tray empty, jammed, or door open	Paper tray empty, paper jam detected, or recorder door opened	unknown
`CHECK SPO2 SENSOR`	SpO2 sensor signal inadequate	SpO2 measurement fails or signal lost	unknown
`CLOCK FAULT 11`	Real time clock oscillator failure	Clock oscillator malfunction at startup	error
`CLOCK FAULT 12`	Real time clock back-up power supply failure	Oscillator stopped at power-up but running when main power applied	error
`CLOCK FAULT 13`	Set time units out of range	Seconds, minutes, year, or other time unit invalid	error
`CONFIRM MANUAL MODE`	User confirmation prompt for manual mode entry	Manual mode selection attempted	info
`DEFIB DISABLED`	Defibrillator function is disabled	Defib disabled configuration or fault	error
`DEFIB FAULT 108`	VMON voltage is less than the target energy during charging	Voltage monitor reads below target during charge	unknown
`DEFIB FAULT 109`	Defib capacitor voltage exceeds selected energy during charging or ready state	Capacitor voltage higher than programmed energy level	unknown
`DEFIB FAULT 111`	Defib capacitor voltage has exceeded absolute maximum acceptable voltage	Capacitor voltage exceeds absolute maximum rating	unknown
`DEFIB FAULT 195`	Current higher than expected during biphasic bridge test or discharge	Excessive current detected during bridge test or after discharge	unknown
`DEFIB FAULT 196`	Biphasic module not operating properly while charging	Biphasic circuit malfunction during charge cycle	unknown
`DEFIB FAULT 71`	Excessive internal defibrillator dumps detected	More than 50 internal dumps in less than 20 minutes	unknown
`DEFIB FAULT 72`	Defibrillator charging inhibited due to voltage out of range	Charging voltage out of acceptable range	unknown
`DEFIB FAULT 76`	Defibrillator capacitor voltage too high for selected energy	Capacitor overvoltage condition	unknown
`DEFIB FAULT 77`	Defibrillator capacitor voltage exceeds absolute rated maximum	Capacitor voltage > absolute maximum rating	unknown
`DEFIB FAULT 78`	Unable to charge defibrillator capacitor	Capacitor charging failure	unknown
`DEFIB FAULT 79`	Defibrillator charging too slowly	Charging time exceeds expected limit	unknown
`DEFIB FAULT 80`	Multiple defibrillator faults detected in rapid succession	4 defibrillator faults within 20 second period	unknown
`DEFIB FAULT 81`	Discharge switch in undefined state	Discharge switch malfunction	unknown
`DEFIB FAULT 84`	Upper discharge transistor shorted	Upper transistor short circuit detected via A/D channel	unknown
`DEFIB FAULT 85`	Lower discharge transistor shorted	Lower transistor short circuit detected via A/D channel	unknown
`DEFIB FAULT 86`	One discharge switch closed during power up test	Discharge switch closure detected during power-up self test	unknown
`DEFIB FAULT 87`	Both discharge switches closed during power up test	Both switches closed simultaneously during power-up self test	unknown
`DEFIB FAULT 94`	Processor fault causing safety monitor port to be non-functional	Safety monitor processor failure	unknown
`DEFIB FAULT 95`	Safe or shutdown line is not functional	Safe/shutdown control line malfunction	unknown
`DEFIB NOT CHARGED`	Discharge button pressed but unit not charged	Discharge button activated when capacitor voltage insufficient	warning
`DEFIB PAD SHORT`	Measured impedance between high voltage leads of MFC is shorted	Low impedance detected between HV output leads	unknown
`DEFIB PAD SHORT`	Test message indicating defibrillator pad cable is functioning correctly when connected to shorting plug	Universal cable connected to test shorting plug when pads not applied to patient	info
`DISABLE SYNC`	Sync mode active when analyze pressed in defibrillator mode	Sync mode enabled during defibrillator analyze	warning
`DISCHARGE FAULT`	Defib capacitor voltage is not decreasing after discharge	Capacitor voltage remains high after discharge attempt	unknown
`ECG FAULT 4`	Communication fault between ECG processor and main processor	ECG/main processor communication link failure	error
`ECG FAULT 5`	ECU RAM test failure or ROM checksum test failure	Memory self-test failure at startup	error
`ECG LEAD OFF`	ECG electrode or cable connection has been lost for one or more leads	Electrode detachment, broken connection, dry gel, or cable fault	warning
`ECG LEAD OFF`	One or more ECG leads are not properly connected when leads are selected	ECG lead detection failure	unknown
`ECG TOO LARGE`	ECG signal too large for accurate shockable rhythm analysis	ECG signal amplitude exceeds analysis range	unknown
`ECG V1 LEAD OFF`	Chest lead V1 is not properly attached to patient	V1 lead connection lost	unknown
`ECG V2 LEAD OFF`	Chest lead V2 is not properly attached to patient	V2 lead connection lost	unknown
`ECG V3 LEAD OFF`	Chest lead V3 is not properly attached to patient	V3 lead connection lost	unknown
`ECG V4 LEAD OFF`	Chest lead V4 is not properly attached to patient	V4 lead connection lost	unknown
`ECG V5 LEAD OFF`	Chest lead V5 is not properly attached to patient	V5 lead connection lost	unknown
`ECG V6 LEAD OFF`	Chest lead V6 is not properly attached to patient	V6 lead connection lost	unknown
`ECG V LEAD OFF`	V LEAD cable is not properly attached	V lead cable connector loose or disconnected	unknown
`ENTER ACCESS CODE`	Manual mode access code is required to enter manual mode	Manual mode selection attempted on AED	info
`ERASING REPORT`	Summary report is being erased from memory	Report erase operation in progress	info
`FAX BUSY`	FAX line at receiving FAX is busy	Remote fax machine line busy	info
`FAX DIALING`	Preparation for sending fax in progress	Fax transmission initiated	info
`FAX DONE`	Fax transmission completed successfully	Fax transmission completed	info
`FAX PREPARING`	System preparing fax for transmission	Fax being prepared for send	info
`FAX SENDING`	Fax transmission in progress	Fax transmission active	info
`INSERT CARD`	No memory card installed in unit	Unit in manual or semi-automated modes without memory card	warning
`LOW BATTERY`	Battery voltage insufficient for continued operation	Battery voltage drops below operating minimum	warning
`NOISY ECG`	Excessive ECG signal noise detected	Number of noisy analysis intervals exceeds threshold	unknown
`NO QRS DETECT`	Unable to detect QRS complex for synchronization	Unit in sync mode with heart rate <20 BPM or QRS amplitude too low	unknown
`NO SHOCK ADV`	No shock recommended by analysis	ECG analysis finds non-shockable rhythm	info
`OPEN AIR DISCHARGE`	Capacitor voltage too high after discharge attempt	Full energy discharge did not occur, capacitor remains charged	unknown
`PACER DISABLED`	Pacing function is disabled	Pacing disabled by configuration or fault	error
`PACER FAULT 115`	Flyback pulse width control circuit not under processor control	Flyback circuit control failure	unknown
`PACER FAULT 116`	Failure to detect XPACE_ON signal	Pace enable signal not detected	unknown
`PACER FAULT 117`	Pace relay is stuck in closed position	Pace relay mechanical failure	unknown
`PACER FAULT 121`	Pace pulse width out of acceptable range	During pacing, pulse width <30ms or >50ms	unknown
`PACER FAULT 122`	Pace current deviation from selected value	Pace current >15mA above and below selected value	unknown
`PACER FAULT 123`	Measured pace rate exceeds selected rate	Pacing rate faster than programmed	unknown
`PACER FAULT 126`	Pace current below selected value threshold	Pace current >15mA below selected value	unknown
`PADDLE FAULT`	Cannot detect accessory type on universal cable	Paddle/accessory type detection failure	error
`PERFORM CPR`	Operator advisory in AED auto defibrillator mode	AED mode operation	info
`POOR LEAD CONTACT`	One or more ECG leads are poorly or not connected	ECG lead detection failure (user configurable)	unknown
`POOR PAD CONTACT`	Defibrillator pads have inadequate contact with patient's skin or electrode connection is unreliable	Loose pad connector, damaged pads, poor pad adhesion to skin, cable connectivity issue	error
`POOR PAD CONTACT`	Electrode impedance exceeds acceptable threshold	High impedance between defibrillation pads	unknown
`PRESS ANALYZE`	Prompt to press analyze button	Operator confirmation needed for rhythm analysis	info
`PRESS CHARGE`	Advisory to charge defibrillator	Shock advised, charging authorized	info
`PRESS SHOCK`	Prompt to deliver shock in AED mode	Defibrillator charged and ready to deliver shock	info
`RECORDER FAULT 142`	Strip chart recorder system error	Strip chart system malfunction	error
`RECORDER FAULT 143`	Strip chart power-up echo test failed	Recorder communication failure at startup	error
`RECORDER FAULT 147`	Strip chart printhead over temperature condition	Printhead temperature exceeds safe limit	error
`RELEASE BUTTONS`	Simultaneous external paddle button presses detected	Both paddle discharge buttons pressed before unit reaches full charge	warning
`RELEASE SHOCK`	Discharge switch closed during charge button press	Discharge activated before unit reaches ready state or during charging	warning
`REPLACE BATTERY`	Battery voltage at absolute minimum threshold	Battery voltage drops below absolute minimum	critical
`REPLACE CARD`	Write errors to memory card during operation	Memory card write failure in manual or semi-automated modes	error
`REPORT FULL`	Summary report memory is full	Summary report storage capacity exceeded	warning
`REPORT HALTED`	Summary report stops printing unexpectedly	Report print failure or interruption	error
`SELECT 30J FOR TEST`	Self test must be run at 30J energy setting	Attempt to run self test at energy other than 30J	warning
`SELECT DEFIB MODE`	Analyze button pressed while in wrong operating mode	Analyze pressed in pacing or monitoring mode	warning
`SELECT LEADS`	12 Lead monitor determined user selected MFE leads	MFE (monitoring) leads selected in 12-lead mode	warning
`SELECT LIMB LEADS`	Limb leads must be selected for continuous analysis	Paddles or augmented leads selected during continuous analysis	warning
`SELECT PADS`	Pads must be selected when using analyze function	Leads I, II, or III selected when analyze pressed	warning
`SET CLOCK`	Real time clock date/time is invalid	Invalid date or time values detected	error
`SET PACE mA`	Pace current setting error or memory corruption	Multiple copy errors in pace current memory	error
`SET PACE RATE`	Pace rate setting error or memory corruption	Multiple copies of pace rate setting do not match	error
`SHOCK ADVISED`	Analysis detects shockable rhythm requiring defibrillation	ECG analysis identifies ventricular fibrillation or pulseless VT	unknown
`SpO2 AMBIENT LIGHT`	Ambient light is too bright for SpO2 sensor operation	Excessive ambient light at sensor location	unknown
`SpO2 COMM ERR`	No communication received from SpO2 module	SpO2 module communication link failure	error
`SpO2 PULSE SEARCH`	SpO2 sensor actively searching for pulse signal	Pulse waveform not yet detected	info
`STAND CLEAR`	Patient rhythm analysis in progress (AED mode only)	Single analysis mode active with defib idle	info
`SYSTEM FAULT 1`	Watchdog timer failure	Watchdog circuit not responding	error
`SYSTEM FAULT 36`	PS_MON (power supply monitor) out of acceptable range	Power supply voltage monitoring circuit fault	error
`SYSTEM FAULT 37`	Disable pacing, defibrillation, and MFE monitoring functions	Critical system fault detected	critical
`SYSTEM FAULT 38`	Failure to shutdown after shutdown order received	System shutdown sequence failure	critical
`SYSTEM FAULT 6`	No communication from ECG unit (ECU) for 4 seconds	ECU communication link timeout	error
`SYSTEM FAULT 7`	A/D converter not performing conversions in timely manner	Analog-to-digital converter performance degraded	error
`TEST FAILED`	Unit failed 30J defibrillator self test	MCU ipeak test (defib peak current) failure at 30J	error
`TEST OK`	Unit passed 30J defibrillator self test	MCU ipeak test (defib peak current) passes at 30J	info
`USE PADDLE DISCHG`	Front panel discharge button pressed with paddles connected	Front panel discharge activated while external paddles or internal spoons connected	warning
`USE PADS`	Must use pads instead of paddles in AED mode	Attempt to defib with paddles in auto defib (AED) mode	warning
`USE PADS TO PACE`	External paddles detected when pacing mode attempted	Paddles connected when pacing mode activated	warning
`USER SETUP REQ`	Configuration and calibration data missing or corrupted	Both copies of stored calibration/config data invalid or never programmed	error
`VF ALARMS OFF`	Ventricular fibrillation alarms disabled	VF alarms disabled in pacing mode or when paddles selected as leads	info
`V LEADS OFF`	V leads (precordial leads) have become disconnected or improperly terminated	V lead terminator unplugged when V leads not in use, or V1 lead metal snap contacting patient skin	warning
`VX LEADS OFF`	Chest lead V (X = lead number) not properly attached	V lead connection lost or not properly attached to patient	unknown
`ZERO CO2 ADAPTER`	New EtCO2 airway adapter requires zeroing calibration	New EtCO2 adapter detected	unknown

Likely causes and actions for each code are in ServiceForge. Connect ServiceForge to your AI

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ServiceForge knowledge base record. Field-unverified unless technicians confirmed it. A teaching summary of the record, not a service manual. Export 2026-10-14.