My honda EU6500is power generator has fault codes E03, E10, and E20 and shuts off. Do you know what these codes means ?

GCU internal failure or inverterunit internal failure.

https://www.manualslib.com/manual/2167496/Honda-Eu65is.html?page=58#manual

I can't find a free download on the internet, most are Owner's manuals or are not for the exact model you want - I don't know how similar similar models are. You might try the following:

http://cdn.powerequipment.honda.com/pe/pdf/manuals/00X31Z376011.pdf (from Honda, EU7000is owner's)
Honda EU7000i Model Info Super Quiet 7000 Watt Inverter Generator Honda...

This is the shop manual for the EU6500is model ($44)
Honda EU6500is Generator Shop Manual
owner's for the EU6500is
http://www.freeproductmanual.com/honda-eu6500is-manual

Finally a link to the search results most of the were taken from
https://uk.search.yahoo.com/search;_ylt=A9mSs2tVBShVngQA_xZLBQx.;_ylc=X1MDMjExNDcxNzAwMwRfcgMyBGZyA2FsdGF2aXN0YQRncHJpZANyOTBfV1hQeVNvT0twcW5oS3NxWlFBBG5fcnNsdAMwBG5fc3VnZwM0BG9yaWdpbgN1ay5zZWFyY2gueWFob28uY29tBHBvcwMwBHBxc3RyAwRwcXN0cmwDBHFzdHJsAzMwBHF1ZXJ5A0hvbmRhIEVVNjUwMGlzQSBzZXJ2aWNlIG1hbnVhbAR0X3N0bXADMTQyODY4NjQ3NQ--?p=Honda+EU6500isA+service+manual&fr2=sb-top-uk.search&fr=altavista

You could try contacting Honda (relevant division) also; if they will provide the manual you want, it might be free

10.April.2015

The manufacturer would be an excellent place to start... and they have superb paper manuals.

If you run 12volts to the carb, will it run? I assume since it has no power at carb as you stated, that it has a fuel shut off at carb and will need voltage to activate magnet.

Yuasa YTZ14S is what mine takes

E 04 means thereis a problem with the govener circut

I have a brand new Honda EU6500 flashing starts but then quits and gives error code E-21. Turns out the rubber batter hold down was undone and blocks air intake so engine quits. Put strap back in place and now runs fine.

It is a inverter protection activation (e-22). Usually followed by e-20,e-10, e-04. Could be a short the inverter or the gcu.

Found These Fault Codes On Internet, Hope This Helps, Daz

ALARM CODES

E00(E00)- Problems with water fill during washing
-Tap closed; solenoid valve, water distributor, wiring ,main PCB, pressure switches

E01(E00)- Problems with water fill during drying
-Tap closed; solenoid valve, wiring , main PCB, pressure switches

E10(E10)- Problems with water drain during washing
-Drain hose kinked, filter blocked, drain pump, water distributor, wiring , main PCB, pressure switches

E11(E10)- Problems with water drain during drying
-Drain hose kinked, filter blocked, drain pump, pressure switches

E20(E20)- Door open
-Cycle in Door delay, wiring , main PCB

E21(E20)- Fault in door delay power triac
-Wiring , main PCB

E30- Fault in electronic pressure switch
-Electronic pressure switch, wiring , main PCB

E31- Fault in electronic pressure switch circuit
-Main PCB (fault in electronic pressure switch circuit)

E32(E10)-Calibration error in electronic pressure switch
-Electronic pressure switch, drain pump, wiring , main PCB, filter blocked

E33- Incongruency between electronic pressure switches and safety switch 1
-Electronic pressure switch, safety pressure switch,wiring, main PCB

E34- Incongruency between electronic pressureswitches and safety switch 2
-Electronic pressure switch, safety pressure switch,wiring, main PCB

E35- Intervention of anti-overflow pressure switch
-Solenoid valve, water distributor, wiring, main PCB,anti-overflow pressure switch

E36- Water leakage (maximum number of resets exceeded)
-Water leakage, drain hose too low, pressure switch,wiring, main PCB

E40- Motor power triac short-circuited
-Main PCB (triac short-circuited)

E41- No signal from tachimetric generator
-Tachimetric generator on motor, wiring, main PCB

E42- Fault in tachimetric generator circuit
-Main PCB (tachimetric generator sensing circuit)

E43- Intervention of motor overload protection
-Motor, wiring, main PCB

E50- Insufficient heating during wash phase
-NTC sensor setting incorrect, heating element, wiring,main PCB

E51- Overheating during wash phase
-Heating element (to earth), main PCB (relays)

E52- Insufficient heating during drying phase
-NTC sensor setting incorrect, safety thermostat,thermostats, drying heater, wiring, main PCB (relays)

E53- Overheating during drying phase
-Drying heater (to earth), main PCB (relays)

E55- Fault in power relay for heating element (K3)
-Safety pressure switch 2, wiring, main PCB- 6 -

E60- Fault in washing NTC sensor
-Washing NTC sensor, wiring, main PCB

E61- Fault in drying NTC sensor(condenser)
-Drying NTC sensor (condenser), wiring, main PCB

E62- Fault in drying NTC sensor(duct)
-Drying NTC sensor (duct), wiring, main PCB

E63- Fault in 1/2 power thermostat
-Drying NTC sensor (duct), 1/2 power thermostat, wiring,main PCB

E70- Power triac to distributor motor short-circuited
-Main PCB (triac short-circuited)

E71- Fault in power relay to distributor loads
-Main PCB (relay open)

E72- No distributor position signal
-Water distributor motor, wiring, main PCB

E73- Incorrect timing on distributor contacts
-Water distributor, wiring, main PCB

E90- Fault in tank fill pump
-Hoses obstructed, tank fill pump, wiring

E91- Fault in tank drain pump
-Hoses obstructed, tank drain pump, wiring

E92- Fault in power triac to tank fill pump
-Tank fill pump, wiring, main PCB