C1604 on Kia: How to Diagnose & Fix
Manufacturer-Specific Chassis Code (Hyundai/Kia: ECU Hardware Error; Nissan: EPS Torque Sensor)
3 Kia models · 3 documented issues · 2 critical · $120-$1,800 repair
C1604 on Kia by model: symptoms, diagnosis and fix
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)
Rio owners have reported Forward Collision-Avoidance Assist warnings, disabled AEB/FCA messages, and occasional false collision alerts even in normal driving. Problems are often linked to the front camera or radar alignment, windshield replacement, sensor obstruction, or software sensitivity. Because the system is part of the active safety suite, repeated faults reduce driver-assistance functionality and can create uncertainty about whether emergency braking is available.
Common Symptoms
- forward safety warning light
- AEB/FCA disabled message
- false collision warning
- warning chime with no obstacle
- driver assistance unavailable
How to Fix
Diagnosis should include scanning the ADAS module for camera/radar communication or calibration faults, checking for windshield damage or replacement history, and inspecting the sensor area for dirt or mounting issues. Recalibration of the front camera/radar, software updates, or replacement of a faulty sensor/module may be required. After repair, a road-test and ADAS calibration confirmation are important.
Owner tips & cautions
- TipIf the warning started after glass replacement, owners frequently recommend confirming that an ADAS camera recalibration was actually performed, not just windshield installation.
- TipKeep the camera/radar area clean and avoid stickers or accessories near the windshield sensor zone.
Sources for this issue (1)
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 3 models: Seltos, Rio, 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?
Published repair estimates on Kia range from $120 to $1,800 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for C1604 on a different make?
View C1604 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.