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Cadillac U2109

Cannot relearn TPM • Specific to Hybrids: – Reduced propulsion power message. – Service high voltage charging system message. Cause If nothing else can be identified as the root ca

DriveNot yet established by verified evidence. If electric power-steering assist is erratic or a reduced-propulsion-power message is displayed, have the vehicle evaluated promptly.
ChargeNot yet established by verified evidence. For a hybrid displaying “Service high voltage charging system,” seek qualified service; the supplied evidence does not establish whether charging can safely continue.
ServiceContact a qualified Cadillac/GM service provider promptly if steering assist is erratic, TPM relearn cannot be completed, or a hybrid displays reduced-propulsion-power or high-voltage-charging-system messages.
Confidence95%

Quick answer

For Cadillac vehicles in the supplied applicability data, U2109 is described as “Cannot relearn TPM.” Official GM/NHTSA bulletin evidence also lists it among codes that may be associated with erratic electric power-steering boost. For hybrids, the bulletin lists possible “Reduced propulsion power” and “Service high voltage charging system” messages. The root cause is not established by the supplied evidence.

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 U2109 mean?

For Cadillac vehicles in the supplied applicability data, U2109 is described as “Cannot relearn TPM.” Official GM/NHTSA bulletin evidence also lists it among codes that may be associated with erratic electric power-steering boost. For hybrids, the bulletin lists possible “Reduced propulsion power” and “Service high voltage charging system” messages. The root cause is not established by the supplied evidence.

2. Technical explanation

The verified diagnostic title identifies U2109 as “Cannot relearn TPM,” referring to an inability to relearn the Tire Pressure Monitoring system. The supplied official manufacturer-communication summaries also identify U2109 as one of several codes potentially associated with erratic electric power-steering boost. Those bulletins separately list hybrid-specific messages: “Reduced propulsion power” and “Service high voltage charging system.” The supplied evidence does not establish that every U2109 event will produce these symptoms, nor does it establish a specific failed component or circuit.

3. What system is affected?

Tire Pressure Monitoring (TPM) relearn function. Official bulletin evidence also associates U2109 with potentially erratic electric power-steering boost; hybrid-specific propulsion-power and high-voltage charging messages are listed in the bulletin evidence.

4. How serious is this code?

Not yet established by verified evidence. However, the supplied official bulletin evidence includes potentially erratic electric power-steering boost and, for hybrids, reduced-propulsion-power and high-voltage-charging-system messages.

5. Symptoms you may notice

  • Service Tire Pressure Monitoring system light illuminated.
  • Cannot relearn TPM.
  • Erratic electric power-steering boost may be associated with U2109.
  • For hybrids: “Reduced propulsion power” message.
  • For hybrids: “Service high voltage charging system” message.

6. Possible causes

  • Not yet established by verified evidence. The supplied bulletin summary states that normal diagnostics should be used to identify the root cause, but the supplied evidence does not identify a specific cause for U2109.

7. Can I still drive the vehicle?

Not yet established by verified evidence. If electric power-steering assist is erratic or a reduced-propulsion-power message is displayed, have the vehicle evaluated promptly.

8. Can I charge the vehicle?

Not yet established by verified evidence. For a hybrid displaying “Service high voltage charging system,” seek qualified service; the supplied evidence does not establish whether charging can safely continue.

9. What you can safely do

  • Record all displayed messages and warning lamps.
  • Do not attempt high-voltage system repairs.
  • Arrange qualified diagnosis if U2109 is stored, especially if steering assist is erratic or hybrid propulsion/charging messages appear.

10. Step-by-step troubleshooting

  1. Use normal manufacturer diagnostic procedures to identify the root cause, as referenced by the official bulletin summary.
  2. Confirm whether the TPM system can be relearned.
  3. Check for other stored diagnostic trouble codes and warning messages. The supplied evidence does not establish a specific troubleshooting sequence beyond normal diagnostics.

11. When to contact service

Contact a qualified Cadillac/GM service provider promptly if steering assist is erratic, TPM relearn cannot be completed, or a hybrid displays reduced-propulsion-power or high-voltage-charging-system messages.

12. What the service center may check

  • Perform normal diagnostics to identify the root cause.
  • Evaluate the reported inability to relearn the Tire Pressure Monitoring system.
  • Evaluate any associated erratic electric power-steering boost.
  • For hybrids, evaluate any reduced-propulsion-power or high-voltage-charging-system message.

13. Possible repair or resolution

  • Not yet established by verified evidence. No specific repair is identified in the supplied evidence.

14. Affected vehicles

15. Related TSBs / service bulletins

  • GM bulletin 13-08-116-001I, published through NHTSA as MC-10239102-0001 on 2023-06-29. It lists U2109 among codes potentially associated with erratic electric power-steering boost, TPM relearn concerns, and hybrid-specific messages. https://static.nhtsa.gov/odi/tsbs/2023/MC-10239102-0001.pdf
  • Earlier supplied revisions: 13-08-116-001H (MC-10222776-0001), 13-08-116-001G (MC-10213767-9999), 13-08-116-001F (MC-10183782-9999), 13-08-116-001E (MC-10163272-9999), and 13-08-116-001C (MC-10140298-9999).

16. Recall information

  • Not yet established by verified evidence. No recall information was supplied.

17. Official manufacturer information

Verified applicability supplied: US-market Cadillac CT6 model years 2014–2023, Cadillac ELR model years 2014–2023, and Cadillac LYRIQ model years 2014–2023. The supplied applicability entries overlap; this does not establish applicability to every configuration within those ranges.

19. Frequently asked questions

What does Cadillac code U2109 mean?

The supplied diagnostic record defines U2109 as “Cannot relearn TPM.”

Can U2109 affect steering?

The supplied official bulletin evidence lists U2109 as potentially associated with erratic electric power-steering boost.

Can U2109 cause hybrid warnings?

The supplied official bulletin evidence lists “Reduced propulsion power” and “Service high voltage charging system” as hybrid-specific messages. It does not establish that U2109 alone causes those messages in every case.

What repairs fix U2109?

Not yet established by verified evidence. The supplied bulletin summary directs normal diagnostics to identify the root cause but does not provide a specific repair in the available evidence.

20. Sources & verification

Verified
Cadillac U2109: Cannot relearn TPM • Specific to Hybrids: – Reduced… | EV Diagnostics