Cause
Faulty DC-DC converter
The hybrid's replacement for an alternator: it steps a few hundred volts from the traction battery down to the fourteen volts that runs everything else on the car. When it fails, the twelve-volt system runs down exactly the way it would with a dead alternator — dimming lights, a battery warning, then a car that dies and will not restart — on a vehicle with no alternator to replace, which is where the diagnosis usually goes wrong first.
One measurement frames everything: with the system READY, the twelve-volt battery should sit around fourteen volts. Resting voltage instead means no charge is arriving — and then the question is whether the converter itself has failed or whether its enable and status wiring (the P0A08–P0A13 families) has stopped telling it to run, which is the cheaper and commoner answer. High-voltage territory throughout: qualified workshops only.
Typically specialist work. Needs equipment or training most home workshops do not have.
Some of these codes mean you should stop driving
1 of the 86 codes this can cause indicate a fault where continuing to drive risks damage or is unsafe. Which one you have matters more than the cause does — read the code's own page before deciding.
Codes this can cause (86)
Codes where this is a likely explanation first, rather than merely a possible one.
- P0A08 DC/DC Converter Status Circuit Likely for this code High
- P0A09 DC/DC Converter Status Circuit Low Likely for this code High
- P0A10 DC/DC Converter Status Circuit High Likely for this code High
- P0A8D 14 Volt Power Module System Voltage Low Likely for this code High
- P0A8E 14 Volt Power Module System Voltage High Likely for this code High
- P0A94 DC/DC Converter A Performance Likely for this code High
- P0C38 DC/DC Converter Temperature Sensor A Circuit Likely for this code High
- P0C39 DC/DC Converter Temperature Sensor A Range/Performance Likely for this code High
- P0C3A DC/DC Converter Temperature Sensor A Low Likely for this code High
- P0C3B DC/DC Converter Temperature Sensor A High Likely for this code High
- P0C3C DC/DC Converter Temperature Sensor A Intermittent/Erratic Likely for this code High
- P0C3D DC/DC Converter Temperature Sensor B Circuit Likely for this code High
- P0C3E DC/DC Converter Temperature Sensor B Range/Performance Likely for this code High
- P0C3F DC/DC Converter Temperature Sensor B Low Likely for this code High
- P0C40 DC/DC Converter Temperature Sensor B High Likely for this code High
- P0C41 DC/DC Converter Temperature Sensor B Intermittent/Erratic Likely for this code High
- P0CA2 DC/DC Converter Step Down Voltage Performance Likely for this code High
- P0CA3 DC/DC Converter Step Up Voltage Performance Likely for this code High
- P0D32 DC/DC Converter A Over Temperature Likely for this code High
- P0E31 DC/DC Converter Voltage Sensor A Circuit Likely for this code High
- P0E32 DC/DC Converter Voltage Sensor A Range/Performance Likely for this code High
- P0E33 DC/DC Converter Voltage Sensor A Low Likely for this code High
- P0E34 DC/DC Converter Voltage Sensor A High Likely for this code High
- P0E35 DC/DC Converter Voltage Sensor A Intermittent/Erratic Likely for this code High
- P0E36 DC/DC Converter Voltage Sensor B Circuit Likely for this code High
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Others who found this
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
Sign in or create an account to add what you found about Faulty DC-DC converter.