Powertrain, generic · Hybrid propulsion

P0A09 DC/DC Converter Status Circuit Low

Check engine lightOn
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

The status signal that the DC/DC converter sends to the hybrid control module stays below its expected range, typically from a short to ground, an open line read as low, or a converter that pulls its status output down because of an internal fault. Mitsubishi uses P0A09 on the 2012-2013 i-MiEV for a DC-DC converter fault; its bulletins tie it to a failed on-board charger that blows the high-voltage fuse feeding the converter, after which the 12 V battery and drive battery stop charging. That usage predates the current split into P0A08, P0A09 and P0A10. Siblings: P0A08 covers the general circuit fault, P0A10 a signal stuck high. Expect warning lights and a 12 V battery that slowly runs flat.

Likely causes

Blown high-voltage fuse feeding the converter, e.g. after an on-board charger failure (Mitsubishi i-MiEV)
DC/DC converter internal fault pulling the status output low
Status line shorted to ground or chafed harness
Faulty input stage in the hybrid/EV control module

Symptoms

  • Power unit, battery or hybrid warning light on
  • 12 V battery not charged, voltage drops
  • On EVs the drive battery may also stop charging

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–2,000
Time1–5 h

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

Parts involved

dcdc converterhigh voltage batterywiring harness

Related codes

P0A08P0A10P0A94P0562

References: static.nhtsa.gov, static.nhtsa.gov, patents.google.com, law.cornell.edu.