P1A90 on Hyundai
DC/DC Converter Input Voltage Sensor Fault (ICCU)
P1A90 on Hyundai vehicles indicates dc/dc converter input voltage sensor fault (iccu). Au7o has documented this code across 1 Hyundai model — most commonly on Ioniq 5. Stored by the Integrated Charging Control Unit, which bundles the on-board charger, DC-DC converter, and vehicle-to-load export hardware into one box. The module reports an implausible or out-of-range input-voltage sensor reading on the DC-DC converter stage, meaning the ICCU can no longer reliably step the high-voltage pack down to charge the 12-volt battery. Hyundai/Kia/Genesis service documentation carries it as the sub-coded fault P1A9096 in the ICCU inspection, fuse-replacement, and software-update campaign. Once the ICCU stops feeding 12 volts, the 12V battery drains and the vehicle progressively loses accessories, then drive power.
Common Causes of P1A90
- •ICCU internal failure (DC-DC converter stage) on E-GMP platform vehicles
- •Blown ICCU input fuse following an ICCU fault event
- •Outdated ICCU control software (addressed by manufacturer software update)
- •12-volt battery repeatedly deep-discharged by a failing ICCU
P1A90 on Hyundai by Model
Hyundai Ioniq 5(1 issue)
- ICCU Failure Causing Loss of Drive Power / 'Turtle Mode' / No DC Fast Charge2022-2024
The Integrated Charging Control Unit (ICCU), which houses the DC-to-DC converter that keeps the 12V battery charged from the high-voltage pack, can suffer overvoltage and thermal overload that blows its internal 12V-feed fuse. When it fails the car may refuse to DC fast charge, charge slowly, drop into reduced-power 'turtle mode' on the highway, or lose all motive power and need a tow. NHTSA recall 24V-204 (March 2024, ~99K vehicles) was followed by a January 2025 expansion covering ~145K vehicles after failures recurred on remedied cars.
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View P1A90 across all makes →Frequently Asked Questions
What does P1A90 mean on Hyundai?▼
P1A90 stands for "DC/DC Converter Input Voltage Sensor Fault (ICCU)." Stored by the Integrated Charging Control Unit, which bundles the on-board charger, DC-DC converter, and vehicle-to-load export hardware into one box. The module reports an implausible or out-of-range input-voltage sensor reading on the DC-DC converter stage, meaning the ICCU can no longer reliably step the high-voltage pack down to charge the 12-volt battery. Hyundai/Kia/Genesis service documentation carries it as the sub-coded fault P1A9096 in the ICCU inspection, fuse-replacement, and software-update campaign. Once the ICCU stops feeding 12 volts, the 12V battery drains and the vehicle progressively loses accessories, then drive power. On Hyundai specifically, this code is documented across 1 model.
What causes P1A90 on Hyundai vehicles?▼
Common causes on Hyundai: ICCU internal failure (DC-DC converter stage) on E-GMP platform vehicles, Blown ICCU input fuse following an ICCU fault event, Outdated ICCU control software (addressed by manufacturer software update), 12-volt battery repeatedly deep-discharged by a failing ICCU. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P1A90 on a Hyundai?▼
Repair costs vary widely depending on the root cause and specific Hyundai model.
Which Hyundai models have P1A90 documented?▼
Au7o has documented P1A90 on 1 Hyundai model: Ioniq 5.