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Hyundai C1604

MDPS ECU (or Power Pack Assy). If DTC returns, replace C-MDPS motor (if app

DriveNot yet established by verified evidence.
ChargeNot yet established by verified evidence.
ServiceService is recommended because the verified Hyundai procedure requires inspection of MDPS wiring/connectors and may require replacement of MDPS components. Whether immediate service is required is not yet established by verified evidence.
Confidence95%

Quick answer

For applicable Hyundai Sonata models, C1604 is identified in Hyundai service communications as an MDPS ECU over/discharge error. The documented repair path is to erase the DTC, check wiring and connectors between the ECU and motor, replace the C-MDPS ECU (or Power Pack assembly) first, and replace the C-MDPS motor if the DTC returns where applicable.

This page separates verified manufacturer/regulator evidence from supporting material. Unsupported causes, repairs or safety conclusions are not guessed.

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1. What does C1604 mean?

For applicable Hyundai Sonata models, C1604 is identified in Hyundai service communications as an MDPS ECU over/discharge error. The documented repair path is to erase the DTC, check wiring and connectors between the ECU and motor, replace the C-MDPS ECU (or Power Pack assembly) first, and replace the C-MDPS motor if the DTC returns where applicable.

2. Technical explanation

MDPS refers to the motor-driven power steering system. Hyundai service communications classify C1604 as an ECU over/discharge error. In the documented flow for this code group, Hyundai directs technicians to first erase the DTC and inspect wiring and connector condition between the ECU and motor. The first component-level replacement listed is the C-MDPS ECU or Power Pack assembly. If the DTC returns, the communication directs replacement of the C-MDPS motor, if applicable.

3. What system is affected?

Motor-Driven Power Steering (MDPS), including the MDPS ECU/Power Pack assembly, motor, and associated ECU-to-motor wiring and connectors.

4. How serious is this code?

Not yet established by verified evidence.

5. Symptoms you may notice

  • A warning lamp illuminated with DTC(s) present is described in Hyundai TSB 22-ST-001H.

6. Possible causes

  • Hyundai identifies C1604 as an MDPS ECU over/discharge error.
  • The documented diagnostic path includes checking wiring and connectors between the ECU and motor.
  • The documented repair path may involve the C-MDPS ECU or Power Pack assembly, followed by the C-MDPS motor if the DTC returns and the motor is applicable.

7. Can I still drive the vehicle?

Not yet established by verified evidence.

8. Can I charge the vehicle?

Not yet established by verified evidence.

9. What you can safely do

  • Have the vehicle diagnosed by a qualified Hyundai service professional using the applicable Hyundai service procedure.
  • Do not attempt component replacement based on the DTC alone.

10. Step-by-step troubleshooting

  1. Erase the DTC.
  2. Check wiring and connector condition between the MDPS ECU and motor.
  3. If required by the applicable Hyundai procedure, replace the C-MDPS ECU or Power Pack assembly first.
  4. If C1604 returns, replace the C-MDPS motor if applicable.

11. When to contact service

Service is recommended because the verified Hyundai procedure requires inspection of MDPS wiring/connectors and may require replacement of MDPS components. Whether immediate service is required is not yet established by verified evidence.

12. What the service center may check

  • Confirm C1604 with a compatible diagnostic tool.
  • Inspect wiring and connectors between the MDPS ECU and motor.
  • Erase the DTC and re-check for its return.
  • Follow the applicable Hyundai repair flow for ECU/Power Pack and motor replacement.

13. Possible repair or resolution

  • Replace the C-MDPS ECU or Power Pack assembly as the first listed component replacement in the Hyundai procedure.
  • If C1604 returns, replace the C-MDPS motor if applicable.

14. Affected vehicles

15. Related TSBs / service bulletins

  • Hyundai TSB 20-ST-001H-1, published August 10, 2020 (NHTSA communication MC-10179244): identifies C1604 as an ECU over/discharge error and provides the ECU-to-motor wiring/connector and replacement sequence.
  • Hyundai TSB 20-ST-001H-2, published September 9, 2020 (NHTSA communication MC-10180981): identifies C1604 as an ECU over/discharge error and provides the ECU-to-motor wiring/connector and replacement sequence.
  • Hyundai TSB 22-ST-001H, published January 6, 2022 (NHTSA communication MC-10207815): includes C1604 in an R-MDPS diagnostic trouble-code repair flowchart for 2015–2017 Sonata (LFA, LF HEV/PHEV).

16. Recall information

  • Not yet established by verified evidence.

17. Official manufacturer information

Verified official NHTSA-hosted Hyundai manufacturer communications: MC-10179244, MC-10180981, and MC-10207815.

19. Frequently asked questions

What does Hyundai DTC C1604 mean?

Hyundai service communications identify C1604 as an MDPS ECU over/discharge error.

What does Hyundai direct technicians to check for C1604?

The documented procedure says to erase the DTC and check wiring and connector condition between the ECU and motor.

What repair is listed if C1604 is present?

The first listed replacement is the C-MDPS ECU or Power Pack assembly. If the DTC returns, Hyundai directs replacement of the C-MDPS motor if applicable.

Which vehicles are supported by the supplied applicability data?

The supplied data lists US-market Hyundai Kona model years 2016–2021 and Hyundai Sonata model years 2016–2021. The supplied 2022 TSB evidence specifically references 2015–2017 Sonata LFA and LF HEV/PHEV.

20. Sources & verification

Verified
Hyundai C1604: MDPS ECU (or Power Pack Assy). If DTC returns, replace… | EV Diagnostics