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Jeep U0423

If multiple LOC DTCs are present: a. Check battery health, system voltage, and TCM (including valve body). b. If TCM goes

DriveNot yet established by verified evidence.
ChargeNot yet established by verified evidence.
ServiceService need is not yet established by verified evidence. However, the verified diagnostic steps involve battery health, system voltage, and TCM/valve-body evaluation, which should be performed by a qualified service technician.
Confidence95%

Quick answer

For verified 2024–2026 US Jeep Grand Cherokee and Wagoneer applicability, U0423 appears in NHTSA Manufacturer Communication 11021842 as a relevant code in a multiple loss-of-communication (LOC) DTC diagnostic context. The communication directs technicians to check battery health, system voltage, and the TCM, including the valve body, when multiple LOC DTCs are present.

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

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DTC Jeep U0423 Short ExplanationMaxidot

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1. What does U0423 mean?

For verified 2024–2026 US Jeep Grand Cherokee and Wagoneer applicability, U0423 appears in NHTSA Manufacturer Communication 11021842 as a relevant code in a multiple loss-of-communication (LOC) DTC diagnostic context. The communication directs technicians to check battery health, system voltage, and the TCM, including the valve body, when multiple LOC DTCs are present.

2. Technical explanation

The supplied official manufacturer communication lists U0423 among relevant DTCs: U0101, U0140, U0155, U0129, U11C3, U0402, U0422, U0423, U0415, and U145D. Its verified instruction is conditional: if multiple LOC DTCs are present, check battery health, system voltage, and the transmission control module (TCM), including the valve body. The supplied evidence also states that the ESM is not the cause in the referenced LOC context because it is not a gateway module. The complete meaning of U0423 beyond this diagnostic context is not yet established by verified evidence.

3. What system is affected?

Communication/network diagnostic context involving multiple LOC DTCs, with checks directed at battery health, system voltage, and the TCM including valve body. A specific affected vehicle system name is not yet established by verified evidence.

4. How serious is this code?

Unknown. The supplied evidence does not assign a severity level.

5. Symptoms you may notice

  • Multiple LOC DTCs may be present. Other vehicle symptoms are not yet established by verified evidence.

6. Possible causes

  • Battery health concern, system-voltage concern, or a TCM/valve-body concern are items the manufacturer communication directs technicians to check when multiple LOC DTCs are present.
  • The actual cause of U0423 is not yet established by verified evidence.
  • In the referenced LOC context, the ESM is stated not to be the cause because it is not a gateway module.

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 service technician retrieve and evaluate all stored DTCs, particularly if multiple LOC DTCs are present.
  • Use the applicable manufacturer diagnostic communication as part of professional diagnosis.

10. Step-by-step troubleshooting

  1. Confirm whether multiple LOC DTCs are present.
  2. Check battery health.
  3. Check system voltage.
  4. Check the TCM, including the valve body.
  5. Do not identify the ESM as the cause in the referenced LOC context; the supplied communication states it is not a gateway module.

11. When to contact service

Service need is not yet established by verified evidence. However, the verified diagnostic steps involve battery health, system voltage, and TCM/valve-body evaluation, which should be performed by a qualified service technician.

12. What the service center may check

  • Retrieve and review all DTCs.
  • Determine whether multiple LOC DTCs are present.
  • Check battery health.
  • Check system voltage.
  • Inspect and diagnose the TCM, including the valve body.

13. Possible repair or resolution

  • A specific repair or resolution is not yet established by verified evidence.

14. Affected vehicles

15. Related TSBs / service bulletins

  • NHTSA Manufacturer Communication 11021842: 9100641, published August 5, 2025. It lists U0423 as relevant in a multiple-LOC-DTC diagnostic procedure and directs checks of battery health, system voltage, and the TCM including valve body.

16. Recall information

  • No recall information was supplied or established by verified evidence.

17. Official manufacturer information

Official source: NHTSA Manufacturer Communication 11021842: 9100641, published August 5, 2025: https://static.nhtsa.gov/odi/ffdd/tsbs/TSBS_RECEIVED_2025-2026.zip#nhtsa_id=11021842

19. Frequently asked questions

What does U0423 mean for the listed Jeep vehicles?

The supplied evidence places U0423 in a list of relevant codes for a multiple LOC DTC diagnostic context. A complete standalone code definition is not yet established by verified evidence.

What should be checked if U0423 occurs with multiple LOC DTCs?

The official communication directs checks of battery health, system voltage, and the TCM, including the valve body.

Is the ESM the cause of this LOC issue?

The supplied communication states that the ESM is not the cause in the referenced LOC context because it is not a gateway module.

Which vehicles are covered by the supplied applicability evidence?

US-market 2024–2026 Jeep Grand Cherokee and 2024–2026 Jeep Wagoneer.

20. Sources & verification

ReferenceVerified
Jeep U0423: If multiple LOC DTCs are present: a. Check battery health,… | EV Diagnostics