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Hyundai C1623

> if present with these DTCs, replace column and housing assembly. If DTC returns, replace MDPS ECU. C1687 CAN time out VSM C1688 VSM signal error  If DTC returns and MDPS is i

DriveNot yet established by verified evidence.
ChargeNot yet established by verified evidence.
ServiceContact a Hyundai dealer or qualified service provider for MDPS/C-MDPS diagnosis. The verified evidence does not establish whether immediate service is required or whether the vehicle is safe to drive.
Confidence95%

Quick answer

For specified U.S. Hyundai Kona and Sonata applications, C1623 is identified in Hyundai C-MDPS material as “CAN time out SAS.” The verified flowchart directs checks of MDPS power/fuse, ground, ECU/VSM CAN line, and GDS communication status; it also directs checking for C1259.

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 C1623 mean?

For specified U.S. Hyundai Kona and Sonata applications, C1623 is identified in Hyundai C-MDPS material as “CAN time out SAS.” The verified flowchart directs checks of MDPS power/fuse, ground, ECU/VSM CAN line, and GDS communication status; it also directs checking for C1259.

2. Technical explanation

C1623 concerns communication between the MDPS/C-MDPS system and SAS, as stated in the verified Hyundai service-bulletin excerpts. The supplied evidence does not establish a single failed component from C1623 alone. Hyundai’s flowchart specifies a diagnostic sequence rather than immediate replacement.

3. What system is affected?

MDPS/C-MDPS (motor-driven power steering) system; CAN communication with SAS. The evidence also references the VSM CAN line.

4. How serious is this code?

Not yet established by verified evidence.

5. Symptoms you may notice

Not yet established by verified evidence.

6. Possible causes

  • A C1623 CAN timeout involving SAS is established by the Hyundai flowchart.
  • The Hyundai flowchart calls for checks of the MDPS/C-MDPS power connector and fuse, ground line, ECU/VSM CAN line, and GDS communication status. The evidence does not establish which of these is the cause on an individual vehicle.
  • C1259 may be relevant because the flowchart specifically directs a check for C1259.

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 a qualified Hyundai service provider diagnose the MDPS/C-MDPS system using the applicable Hyundai flowchart.
  • Provide all stored DTCs, including whether C1259 is present, because the verified flowchart specifically references C1259.

10. Step-by-step troubleshooting

  1. Verify C1623 with Hyundai GDS communication status, as specified in the Hyundai flowchart.
  2. Check the MDPS/C-MDPS power connector and fuse.
  3. Check the MDPS/C-MDPS ground line.
  4. Check the MDPS/C-MDPS ECU/VSM CAN line.
  5. Check for DTC C1259.
  6. These are manufacturer diagnostic steps and should be performed by qualified service personnel.

11. When to contact service

Contact a Hyundai dealer or qualified service provider for MDPS/C-MDPS diagnosis. The verified evidence does not establish whether immediate service is required or whether the vehicle is safe to drive.

12. What the service center may check

  • MDPS/C-MDPS power connector and fuse check.
  • MDPS/C-MDPS ground-line check.
  • MDPS/C-MDPS ECU/VSM CAN-line check.
  • GDS communication-status check.
  • Check for C1259.

13. Possible repair or resolution

  • If C1259 is present with the specified DTCs, Hyundai’s flowchart directs replacement of the column and housing assembly.
  • If the DTC returns after that step, Hyundai’s flowchart directs replacement of the MDPS ECU; some bulletin versions describe this as the MDPS ECU or Power Pack Assembly.
  • No repair outcome is established by verified evidence for C1623 without the specified diagnostic findings.

14. Affected vehicles

15. Related TSBs / service bulletins

  • Hyundai TSB 23-ST-003H, published April 10, 2023: C-MDPS DTC repair flowchart. NHTSA manufacturer communication MC-10235349-0001: https://static.nhtsa.gov/odi/tsbs/2023/MC-10235349-0001.pdf
  • Hyundai TSB 22-ST-001H, published January 6, 2022: C-MDPS DTC repair flowchart. NHTSA manufacturer communication MC-10207815-0001: https://static.nhtsa.gov/odi/tsbs/2022/MC-10207815-0001.pdf
  • Hyundai TSB 20-ST-001H-2, published September 9, 2020. NHTSA manufacturer communication MC-10180981-0001: https://static.nhtsa.gov/odi/tsbs/2020/MC-10180981-0001.pdf
  • Hyundai TSB 20-ST-001H-1, published August 10, 2020. NHTSA manufacturer communication MC-10179244-0001: https://static.nhtsa.gov/odi/tsbs/2020/MC-10179244-0001.pdf
  • Hyundai TSB 20-ST-001H, published January 3, 2020. NHTSA manufacturer communication MC-10170896-0001: https://static.nhtsa.gov/odi/tsbs/2020/MC-10170896-0001.pdf
  • Hyundai TSB 19-ST-001H, published April 22, 2019. NHTSA manufacturer communication MC-10160106-9999: https://static.nhtsa.gov/odi/tsbs/2019/MC-10160106-9999.pdf

16. Recall information

No recall relationship is established by verified evidence.

17. Official manufacturer information

Verified official sources are Hyundai manufacturer communications filed with NHTSA. Supplied applicability evidence lists U.S. Hyundai Kona model years 2016–2021 and U.S. Hyundai Sonata model years 2016–2021, with overlapping year ranges across the supplied records. Exact vehicle applicability should be confirmed using the applicable Hyundai bulletin and vehicle information.

19. Frequently asked questions

What does Hyundai C1623 mean?

The verified Hyundai flowchart identifies C1623 as “CAN time out SAS.”

What does Hyundai direct technicians to check for C1623?

The flowchart directs checks of the MDPS/C-MDPS power connector and fuse, ground line, ECU/VSM CAN line, GDS communication status, and C1259.

Does C1623 mean the MDPS ECU must be replaced?

Not from C1623 alone. The verified flowchart first specifies diagnostic checks. If C1259 is present with the specified DTCs, it directs replacement of the column and housing assembly; if the DTC returns, it directs replacement of the MDPS ECU or, in some versions, the MDPS ECU/Power Pack Assembly.

Can I drive or charge with C1623?

Not yet established by verified evidence.

20. Sources & verification

Verified
Hyundai C1623: > if present with these DTCs, replace column and… | EV Diagnostics