C1604 on Kia: How to Diagnose & Fix
Manufacturer-Specific Chassis Code (Hyundai/Kia: ECU Hardware Error; Nissan: EPS Torque Sensor)
2 Kia models · 2 documented issues · 1 critical
C1604 on Kia by model: symptoms, diagnosis and fix
On 2021 Seltos (SP2) built January 20, 2021 to February 10, 2021 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)
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)
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 on a Kia?
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. On Kia it is documented across 2 models: Seltos, Soul.
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 on a Kia?
Repair costs vary widely with the root cause and Kia model; each issue on this page carries its own estimate where one is published.
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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.