Powertrain, generic · Hybrid propulsion

P0D18 Battery Charging System A High Voltage Interlock Circuit High

Check engine lightOn
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

P0D18 flags a charging HVIL signal that sits too high. On the Chevrolet Volt and Cadillac ELR GM tests the loop in two states: with the 5 V source off, a sensed level above 24 % of reference (5 of 6 samples in 2011, 5 of 8 for 2014 and ELR), and with it on, a level above 44 % (4 of 6), set the code as Type A, MIL after one trip. A high value may point to a break or added resistance in the loop or a short to a voltage. Polestar stores P0D1800 in the BECM of the 2021–2023 Polestar 2 with a propulsion warning and resolves it with BECM software 2.10 (TJ 36713). Kia lists P0D1812 for the 2023 Niro EV among the codes that lead to ICCU replacement (bulletin 298). The low case is P0D17, the open loop P0D15.

Likely causes

High resistance or partial break in the interlock loop
Battery module software needing an update (Polestar 2)
Faulty integrated charging unit (Kia Niro EV ICCU)
Interlock wire shorted to a voltage source

Symptoms

  • Malfunction indicator lamp (GM Type A)
  • Propulsion or high-voltage warning in the cluster
  • Slow or no AC charging

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€50–3,000
Time0.5–5 h

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

Parts involved

bcs a hv interlockwiring harnesson board chargerhybrid control module

Related codes

P0D15P0D16P0D17P0D19P0A0D

References: gsi.ext.gm.com, gsi.ext.gm.com, static.nhtsa.gov, static.nhtsa.gov.