P1A90 on Genesis: How to Diagnose & Fix
DC/DC Converter Input Voltage Sensor Fault (ICCU)
1 Genesis model · 1 documented issue · 1 critical
P1A90 on Genesis by model: symptoms, diagnosis and fix
The Integrated Charging Control Unit (ICCU) manages charging of the high-voltage pack and the 12V battery that runs accessories and control modules. The ICCU (and its internal fuse) can become damaged and stop charging the 12V system. The car then enters a fail-safe mode with warning lights, audible alerts, and reduced power; if driving continues it can fully lose drive power, sometimes preceded by an audible 'pop.' Drivers typically have ~22-45 minutes to pull over, with steering and brakes still functional. Genesis covered this under recalls tied to NHTSA 24V-204, expanded/replaced by Genesis 025G (Dec 2024), part of the broad Hyundai/Kia/Genesis ICCU campaign. The failed ICCU also produces dead-12V 'bricked' no-start events.
Common Symptoms
- Loss of drive power / reduced propulsion while driving
- Audible 'pop' then warning lights and alarms
- Repeated dead 12V battery / no-start ('bricked')
- Vehicle fails to DC fast charge or AC charge
- Check electric vehicle system warning
How to Fix
Verify the VIN against the ICCU recalls (Genesis 025G; NHTSA 24V-204 and its expansions). Dealers inspect and replace the ICCU and its fuse as necessary and apply updated ICCU software, free of charge. If you experience warning lights plus a power-reduction message, pull over and arrange transport rather than continuing to drive. A repeat dead-12V battery on an Electrified GV70 should trigger an ICCU diagnosis, not just a battery swap.
Sources for this issue (1)
P1A90 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P1A90 mean on a Genesis?
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 Genesis it is documented across 1 model: GV70.
What are the most common causes of P1A90?
The most common causes of P1A90 are: 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. The specific cause varies by vehicle.
How much does it cost to fix P1A90 on a Genesis?
Repair costs vary widely with the root cause and Genesis model; each issue on this page carries its own estimate where one is published.
Looking for P1A90 on a different make?
View P1A90 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.