P0A09
DC/DC Converter Status Circuit Low Input
- Severity
- High
- Driving
- Drive only to a garage
The DC/DC converter status circuit is reading low - typically a short to earth or an open circuit. The module cannot tell whether the converter is charging the 12 volt system, so it cannot rely on it. On these vehicles the DC/DC converter does the job an alternator does on a conventional car, and nothing else can do it.
Possible causes
- CommonWiring a short to earth or an open circuit on the status circuit
- CommonCorroded or damaged connector
- CommonFailed DC/DC converter
- PossibleBlown fuse in the converter's supply or output
- RareFailed control module input
What you might notice
- 12 volt battery going flat
- Multiple unrelated warning lights
- Vehicle powering down unexpectedly
- Dim lights, or a battery warning lamp
What to check, in order
- Measure the 12 volt system voltage with the vehicle powered up. Around 14 volts means the converter is working and the fault is in the status circuit; around 12 and falling means the converter itself.
- Check the converter's fuses on both sides.
- Inspect the status circuit connector and wiring for corrosion and damage.
- Replace the 12 volt battery only after the converter is confirmed working, not before.
- Stop at the 12 volt system. Anything further needs the manufacturer's high-voltage procedure.
Read this code from your own car
Plug an ELM327 adapter into the OBD-II port under the dashboard. Pin16 reads every stored, pending and permanent code, explains each one like this page does — offline, with no account — and shows what the car recorded when the fault was set.
Where this code sits
P00xxP01xxP02xxP03xxP04xxP05xxP06xxP07xxP08xxP09xxP0AxxP0BxxP0CxxP0DxxP0ExxP0FxxP10xxP11xxP12xxP13xxP14xxP15xxP16xxP17xxP18xxP19xxP1AxxP1BxxP1CxxP1DxxP1ExxP1FxxP20xxP21xxP22xxP23xxP24xxP25xxP26xxP27xxP28xxP29xxP2AxxP2BxxP2CxxP2DxxP2ExxP2FxxP30xxP31xxP32xxP33xxP34xxP35xxP36xxP37xxP38xxP39xxP3AxxP3BxxP3CxxP3DxxP3ExxP3Fxx