P0A08: DC/DC Converter Status Circuit

General fault on the status line through which the DC/DC converter reports its condition to the hybrid control module. The converter replaces the alternator: it steps the traction battery voltage down to charge the 12 V battery. When its self-diagnosis detects an internal problem it signals this back, and the controller reacts. P0A08 is the broad verdict for an unusable or implausible status signal; a signal stuck low or high has its own codes P0A09 and P0A10. No manufacturer documents P0A08 publicly in an official source. Toyota's Prius c recall shows the consequence of a dead converter: warning lights, then a draining 12 V battery that can shut the hybrid system down. Drivers should not keep driving for long.

High severity. Can I keep driving?If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.

Symptoms

Hybrid system, battery or master warning light on
12 V battery is no longer charged and voltage drops while driving
Electrical consumers fail and the hybrid system may finally shut down

Most likely causes

Internal fault in the DC/DC converter reported by its self-diagnosis
Damaged or corroded status line or connector between converter and hybrid control module
Converter overheating due to a fault in the inverter/converter coolant loop
Faulty input stage in the hybrid control module

What to check, in order

Start with the simplest. You can tick off each step.

Read the codes with a hybrid-compatible scanner and write down the freeze frame data
Make sure the battery cooling air intake is clean
Check the 12 V auxiliary battery, which can also trigger warnings
Leave any high-voltage measurements to a specialized repair shop

Good to know

Repair difficulty: hard
It can trigger limp mode.

What each character of P0A08 means

P: Powertrain: engine and transmission
0: Generic code: same on every make
A: Hybrid or air and fuel
08: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0A08?

If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.

What causes code P0A08?

The most common causes are: internal fault in the DC/DC converter reported by its self-diagnosis; damaged or corroded status line or connector between converter and hybrid control module; converter overheating due to a fault in the inverter/converter coolant loop.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.