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Jeep U1123

00 Lost Communication with Lin ECU 3 U113D-00 Lost Communication with Master Power Window Switch (Set by PDM only). Repair Procedure: Vehic

DriveNot yet established by verified evidence.
ChargeNot yet established by verified evidence.
ServiceContact an authorized Jeep dealer or qualified service facility. Ask them to review manufacturer communication S2408000016 and confirm VIN applicability.
Confidence95%

Quick answer

U1123-00 is documented as “Lost Communication with LIN ECU 3.” For certain 2023–2026 US Jeep Grand Cherokee and Wagoneer vehicles, an official manufacturer communication associates this code with door-function concerns and a defined repair procedure.

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 U1123 mean?

U1123-00 is documented as “Lost Communication with LIN ECU 3.” For certain 2023–2026 US Jeep Grand Cherokee and Wagoneer vehicles, an official manufacturer communication associates this code with door-function concerns and a defined repair procedure.

2. Technical explanation

Verified evidence identifies U1123-00 as a lost-communication fault involving LIN ECU 3. The cited manufacturer communication also lists U1122-00 and U113D-00 in connection with the same door-function concern. U113D-00 is identified as “Lost Communication with Master Power Window Switch” and is set by the PDM only. The supplied evidence does not establish the underlying component-level cause of U1123-00.

3. What system is affected?

Door-related LIN communication; the exact system name is not separately established by the supplied diagnostic record.

4. How serious is this code?

Not yet established by verified evidence.

5. Symptoms you may notice

  • Doors may not function.
  • Earlier bulletin revisions describe concerns in which the rear and/or rear-left doors do not function.
  • A technician may find U1123-00, potentially alongside U1122-00 and U113D-00.

6. Possible causes

  • A loss of communication with LIN ECU 3 is established by the code definition.
  • The specific root cause is not yet established by verified evidence.

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

  • Arrange diagnosis by an authorized Jeep service facility if door functions are inoperative or U1123-00 is stored.
  • Do not attempt high-voltage repairs; no high-voltage involvement is established by the supplied evidence.
  • Provide the technician with DTC U1123-00 and manufacturer communication S2408000016.

10. Step-by-step troubleshooting

  1. Use a suitable diagnostic scan tool to confirm the stored DTCs. Further diagnostic steps are not established by the supplied evidence.
  2. Check whether the vehicle is a covered US 2023–2026 Jeep Grand Cherokee or Wagoneer. Exact VIN eligibility and repair applicability must be confirmed by a dealer.

11. When to contact service

Contact an authorized Jeep dealer or qualified service facility. Ask them to review manufacturer communication S2408000016 and confirm VIN applicability.

12. What the service center may check

  • Confirm whether U1123-00 is stored in the BCM, as described in the cited manufacturer communication.
  • Check for U1122-00 Lost Communication with LIN ECU 2 and U113D-00 Lost Communication with Master Power Window Switch; U113D-00 is set by the PDM only.
  • Confirm the reported door-function condition and apply the manufacturer communication’s repair procedure when applicable.

13. Possible repair or resolution

  • The official manufacturer communication S2408000016 contains a repair procedure for affected vehicles.
  • The supplied evidence does not provide enough detail to state the specific repair steps or parts involved.

14. Affected vehicles

15. Related TSBs / service bulletins

  • S2408000016 REV.E, NHTSA manufacturer communication MC-11031243-0001, published March 31, 2026.
  • S2408000016 REV.D, NHTSA manufacturer communication MC-11030040-0001, published March 4, 2026.
  • S2408000016 REV.C, NHTSA manufacturer communication MC-11021847-0001, published August 6, 2025.
  • S2408000016 REV.B, NHTSA manufacturer communication MC-11008907-0001, published October 11, 2024.
  • S2408000016 REV.A, NHTSA manufacturer communication MC-11005275-0001, published July 26, 2024.

16. Recall information

  • Not yet established by verified evidence.

17. Official manufacturer information

Official NHTSA-hosted manufacturer communication: S2408000016 REV.E, MC-11031243-0001: https://static.nhtsa.gov/odi/tsbs/2026/MC-11031243-0001.pdf

19. Frequently asked questions

What does Jeep code U1123-00 mean?

It means “Lost Communication with LIN ECU 3,” based on the supplied diagnostic record and official manufacturer communication.

What problems can occur with U1123-00?

The official communication associates the listed DTCs with door-function concerns. It does not establish every possible symptom.

Which vehicles are covered by the supplied evidence?

US-market 2023–2026 Jeep Grand Cherokee and Wagoneer entries are supplied. VIN-specific applicability must be confirmed by a dealer.

Is U1123-00 a recall?

Not yet established by verified evidence. The supplied sources are manufacturer communications/TSBs, not recall records.

20. Sources & verification

Verified
Jeep U1123: 00 Lost Communication with Lin ECU 3 U113D-00 Lost… | EV Diagnostics