The 14 V power module (DC/DC converter) regulates the voltage of the 12 V network in hybrid and electric vehicles. P0A8B is the general code for a fault in the voltage this module produces or senses, without the more specific labels unstable, low, high or performance (P0A8C to P0A8F). No manufacturer documents this code publicly. GM's 2013 eAssist tables show how the sibling codes are used for the same function: the APM low-voltage sensor is checked against fixed limits and against the separately measured run/crank voltage. A fault here means the 12 V system may no longer be supplied reliably, so the 12 V battery and consumers should be checked before the module is condemned.
Medium severity. Can I keep driving?If the battery warning light comes on, you could get stranded. Turn off electrical accessories and go straight to a repair shop.
Symptoms
- Charging or hybrid system warning
- Electrical consumers behave erratically
- 12 V battery discharged
Most likely causes
- Internal fault of the DC/DC converter
- Loose or corroded 12 V output cable or ground connection
- Weak 12 V battery distorting the system voltage
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- It affects emissions.
What each character of P0A8B means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- A: Hybrid or air and fuel
- 8B: Specific fault in that system
Frequently asked questions
Can I keep driving with code P0A8B?
If the battery warning light comes on, you could get stranded. Turn off electrical accessories and go straight to a repair shop.
What causes code P0A8B?
The most common causes are: internal fault of the DC/DC converter; loose or corroded 12 V output cable or ground connection; weak 12 V battery distorting the system voltage.
Related codes
- P0A8C14 Volt Power Module System Voltage Unstable
- P0A8D14 Volt Power Module System Voltage Low
- P0A8E14 Volt Power Module System Voltage High
- P0A8F14 Volt Power Module System Performance
- P0562System Voltage Low
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.