Code 43
Onan
DC Bus Overvoltage
Generator shuts down; Code 43 displayed indicating DC overvoltage
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Faulty battery charger, Incorrect external charging source connected, Failed controller voltage regulation, Loose battery connections causing spikes
How to Fix / Troubleshooting
Safety first: Disable auto-start and disconnect external chargers before working on the DC system.
- Measure battery voltage: With the unit off, measure DC voltage at the battery. If significantly above normal (e.g., >15 V on a 12 V system), disconnect the onboard charger and any external chargers.
- Inspect battery charger: Locate the Onan battery charger module. Check for overheating or damage. Replace if it outputs excessive voltage.
- Check battery connections: Tighten and clean all battery terminals to prevent intermittent connections that can cause voltage spikes.
- Controller check: If overvoltage persists with a known-good charger, the controller’s DC regulation may be faulty and require replacement.
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Repair Difficulty
Hard
4/5
Required Part
Battery Charger Module
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