Powertrain, generic · Hybrid propulsion

P0A8B 14 Volt Power Module System Voltage

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

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.

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

Symptoms

  • Charging or hybrid system warning
  • Electrical consumers behave erratically
  • 12 V battery discharged

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–1,800
Time1–4 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

pm14v moduledcdc converter

Related codes

P0A8CP0A8DP0A8EP0A8FP0562

References: law.cornell.edu, gsi.ext.gm.com.