C1604: How to Diagnose & Fix — Manufacturer-Specific Chassis Code (Hyundai/Kia: ECU Hardware Error; Nissan: EPS Torque Sensor)
4 vehicles · 3 makes · $200-$1,800 repair
How to diagnose and fix C1604: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Kia Seltos · 2021–2021
On early-build 2021 Seltos (SP2) the Electric Power Steering module logs DTC C160404 during its start-up diagnostic self-check and illuminates the steering warning light. In most cases the hardware is fine — the module's judgment logic is over-sensitive during the power-up check, particularly when battery voltage sags at cranking. Kia addressed it with bulletin CHA110 / campaign SA466, an EPS ECU reflash titled 'SP2 EPS MIL ON DTC (C160404) JUDGMENT LOGIC IMPROVEMENT'. Because the fault can appear as a hard warning light, owners are frequently quoted a full EPS rack replacement when a reflash is the actual repair.
Common Symptoms
- EPS / steering warning light on at startup
- Message indicating power steering system check
- Heavier steering effort in some occurrences
- Fault more likely with a weak or partly discharged 12V battery
How to Fix
Reprogram the EPS control unit with KDS per TSB CHA110 / SA466 — free under warranty. Kia's procedure requires a fully charged battery reading 12.3 V or higher, or a jump box connected, because a low-voltage flash can brick the module. Before authorizing any rack or motor replacement for a C160404, insist the EPS software level be checked against the campaign. If the code returns after the flash, then diagnose the EPS motor/torque sensor and the battery and charging system, since low system voltage reproduces the fault.
Sources for this issue (2)
Genesis G70 · 2019–2021
An electrical short circuit can develop inside the Anti-lock Brake System (ABS) hydraulic control module. Because the module is always powered, the short can cause an engine-compartment fire whether the vehicle is parked or being driven, even with the ignition off. Genesis recalled certain 2019-2021 G70 vehicles under NHTSA campaign 21V-161 (Genesis recall 007G); owners were told to park the car outside and away from structures until repaired. This is part of the broader Hyundai/Genesis ABS-fire recall family. The remedy installs a fuse in the ABS module wiring to prevent the short from igniting a fire.
Common Symptoms
- Burning or melting-plastic smell from the engine bay
- ABS / brake / traction-control warning lights illuminated
- Smoke from under the hood while parked or driving
- Blown fuses related to the ABS circuit
How to Fix
Confirm the VIN against Recall 21V-161 (007G) and have the free remedy performed — dealers add a multi-fuse to the ABS module's power supply so a short can't start a fire. Until repaired, park outdoors away from buildings. If the ABS warning light is on or the module has already been damaged, the hydraulic electronic control unit (HECU/ABS module) is inspected and replaced as needed.
Sources for this issue (1)
Kia Soul · 2011–2013
The Hydraulic Electronic Control Unit (HECU/ABS module) can develop an internal electrical short (fluid leakage plus localized PCB melting was found in retrieved units), producing excessive current that can cause an engine-compartment fire while parked or driving. NHTSA recall 23V-652 covers 349,309 2011-2013 Souls equipped with Electronic Stability Control, part of the broader Kia/Hyundai 'park outside' fire-risk campaign. Owners were told to park outside and away from structures until repaired.
Common Symptoms
- Burning smell from engine bay
- Smoke under hood
- ABS/brake warning light
- Fire while parked or driving
How to Fix
Recall remedy: dealer installs new fuse(s) in the HECU electrical circuit to prevent an overcurrent condition, free of charge under NHTSA 23V-652 (Kia SC284). Interim notices mailed late 2023; remedy available as of mid-2024.
Sources for this issue (3)
Hyundai Veloster · 2019–2021
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C1604 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 C1604 mean?
C1604 stands for "Manufacturer-Specific Chassis Code (Hyundai/Kia: ECU Hardware Error; Nissan: EPS Torque Sensor)." C1604 is a manufacturer-specific chassis code whose meaning depends on the maker. On Hyundai/Kia it generally indicates an internal ECU/control-module hardware error detected during the module's self-diagnostics (processor, memory, or internal power fault). On Nissan/Infiniti it has been associated with an electric power steering torque sensor fault. Because it disables a safety system (ABS/ESC or electric power steering) as a fail-safe, the affected feature may not work until repaired, so confirm the exact definition for the specific vehicle.
What are the most common causes of C1604?
The most common causes of C1604 are: Internal control module (EBCM/ESC or EPS) hardware fault, Electric power steering torque sensor fault (Nissan/Infiniti), Low or unstable supply voltage to the module, Corroded or loose module connector, Wiring or ground fault, Software/calibration issue requiring update. The specific cause varies by vehicle.
How much does it cost to fix C1604?
Repair costs for C1604 range from $200 to $1,800, depending on the vehicle and root cause.
Which vehicles are affected by C1604?
Au7o has documented C1604 across 4 vehicle models from 3 manufacturers: Genesis, Hyundai, Kia.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.