Powertrain, generic · Hybrid propulsion

P0AA0 Hybrid/EV Battery Positive Contactor Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

The positive main contactor is a high-voltage relay that connects the positive pole of the traction battery to the propulsion bus. P0AA0 is the general fault code for this contactor circuit, used when the controller sees a problem it does not split into stuck closed (P0AA1), stuck open (P0AA2) or the control-circuit codes P0AD9 to P0ADC. No manufacturer documents this exact code publicly; GM, Audi, Jeep and Mitsubishi report the specific siblings instead. NHTSA's Mach-E recall query shows the underlying failure modes: overheated contacts that stay open or weld shut. With the positive side unusable the car may refuse ready mode or drop propulsion; work on it requires high-voltage qualification.

Likely causes

Positive contactor or battery junction box worn or damaged
Fault in the contactor coil feed or its connector
Weak 12 V supply so the contactor does not pull in reliably

Symptoms

  • Vehicle does not enter ready or propulsion-active mode
  • Hybrid or EV system warning with check engine light
  • Possible loss of propulsion while driving

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€150–3,000
Time1–6 h

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

Parts involved

hv battery positive contactorwiring harnessbms

Related codes

P0AA1P0AA2P0AA3P0AD9P0ADA

References: law.cornell.edu, gsi.ext.gm.com, static.nhtsa.gov.