Hyundai Kia Error Code P1723: How to Fix It

Medium 1-2 hours High Severity Verified June 2026
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Error Code
P1723
Brand
Hyundai Kia
Product Type
automotive
Severity
High
DIY Difficulty
Medium
Estimated Fix Time
1-2 hours
Error code P1723 in Hyundai and Kia vehicles indicates a problem with the automatic transmission (AT) control relay's range or performance. This error affects the transmission's electronic control system and can cause shifting problems, reduced power, or transmission protection mode activation.
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Tools You'll Need

How to Fix Error Code P1723

  1. Turn off engine and engage parking brake

    Never work on electrical components with the engine running or ignition on. Hot engine components can cause burns.

  2. Connect OBD2 scanner and confirm error code

  3. Locate the AT control relay in the engine bay fuse box

    Disconnect the negative battery terminal before removing any relays to prevent electrical shorts.

  4. Inspect AT control relay for physical damage

  5. Test relay operation with multimeter

  6. Perform relay swap test

  7. Check relay socket wiring and connections

  8. Replace faulty relay or repair wiring

    Use only OEM or equivalent quality relays. Cheap aftermarket relays may cause recurring problems.

  9. Clear codes and test drive

Parts You May Need

Automatic transmission control relay
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Electrical connector
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Automotive electrical wire
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Automatic transmission control relay
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Electrical connector
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Automotive electrical wire
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Automatic transmission control relay
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Electrical connector
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Automotive electrical wire
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Automatic transmission control relay
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Electrical connector
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Automotive electrical wire
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Automatic transmission control relay
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Electrical connector
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Automotive electrical wire
Check Price on Amazon
Automatic transmission control relay
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Electrical connector
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Automotive electrical wire
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When to Call a Professional

If the relay and wiring test good but P1723 persists, the transmission control module (TCM) may be faulty and require professional diagnosis. Also seek professional help if you're uncomfortable working with electrical systems or if multiple transmission-related codes appear simultaneously.

Frequently Asked Questions

Can I drive with P1723 error code?
It's not recommended to drive with P1723 as it can cause transmission to enter limp mode, unpredictable shifting, or complete transmission failure. Have it diagnosed and repaired promptly.
What causes P1723 in Hyundai and Kia vehicles?
P1723 is typically caused by a faulty AT control relay, corroded relay connections, damaged wiring to the transmission control module, or in rare cases, a failing TCM itself.
How much does it cost to fix P1723?
If it's just a bad relay, expect $15-50 for the part. If wiring repair is needed, costs can range $100-300. TCM replacement, if required, can cost $800-1500 including labor.
Will P1723 cause transmission damage?
If ignored, P1723 can lead to transmission overheating, erratic shifting, and potential internal transmission damage. Address the issue promptly to avoid costly transmission repairs.

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