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Audi U121C00

Drive Motor “A” No Communication

DriveNot yet established by verified evidence.
ChargeNot yet established by verified evidence.
ServiceService evaluation is appropriate because the verified Audi communication associates this DTC with potential chafing of a power-electronics 12V wiring harness.
Confidence95%

Quick answer

For a 2020 Audi Q5 in the US, DTC U121C00 means “Drive Motor ‘A’ No Communication.” Audi’s official service communication identifies possible chafing of the 12V wiring harness for the power electronics (J841, address word 0051) against underbody trim as the technical background for a bulletin that includes this DTC.

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 U121C00 mean?

For a 2020 Audi Q5 in the US, DTC U121C00 means “Drive Motor ‘A’ No Communication.” Audi’s official service communication identifies possible chafing of the 12V wiring harness for the power electronics (J841, address word 0051) against underbody trim as the technical background for a bulletin that includes this DTC.

2. Technical explanation

The verified Audi/NHTSA service communication lists U121C00 among example DTCs associated with the 12V wiring harness for the power electronics, J841 (address word 0051). The bulletin states that this harness can chafe against the underbody trim. It also states that harness routing was improved in production.

3. What system is affected?

Verified evidence identifies the 12V wiring harness for the power electronics, J841 (address word 0051).

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

  • The 12V wiring harness for the power electronics, J841 (address word 0051), can chafe against underbody trim, according to the Audi service communication.

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 Audi-qualified service facility.
  • Do not attempt high-voltage system repair based on this code.

10. Step-by-step troubleshooting

  1. A service facility can evaluate the 12V wiring harness for the power electronics, J841 (address word 0051), in relation to the underbody trim, consistent with the Audi service communication.
  2. The verified source does not establish a complete diagnostic procedure or a specific repair for every occurrence of U121C00.

11. When to contact service

Service evaluation is appropriate because the verified Audi communication associates this DTC with potential chafing of a power-electronics 12V wiring harness.

12. What the service center may check

  • Inspect the 12V wiring harness for the power electronics, J841 (address word 0051), for chafing against underbody trim, as applicable to the Audi service communication.
  • Confirm whether the vehicle is a 2020 Audi Q5 for the US market, the verified applicability in the supplied evidence.

13. Possible repair or resolution

  • The bulletin states that harness routing was improved in production.
  • The supplied evidence does not establish the exact field repair or parts required for an individual vehicle.

14. Affected vehicles

15. Related TSBs / service bulletins

  • NHTSA Manufacturer Communication PDF 10191577: A9421372063075_1, published April 30, 2021. It includes U121C00 as an example DTC and identifies possible chafing of the J841 power-electronics 12V wiring harness against underbody trim. Source: https://static.nhtsa.gov/odi/tsbs/2021/MC-10191577-0001.pdf

16. Recall information

No recall relationship is established by verified evidence.

17. Official manufacturer information

Verified applicability: 2020 Audi Q5, US. Verified official source: NHTSA-hosted Audi manufacturer communication MC-10191577-0001, published April 30, 2021.

19. Frequently asked questions

What does Audi code U121C00 mean?

It means “Drive Motor ‘A’ No Communication.”

What vehicle applicability is verified?

The supplied evidence verifies applicability to the 2020 Audi Q5 in the US.

What condition does the Audi service communication identify?

It identifies that the 12V wiring harness for the power electronics, J841 (address word 0051), can chafe against underbody trim.

Is it safe to drive or charge with U121C00?

Not yet established by verified evidence.

20. Sources & verification

Verified
Audi U121C00: Drive Motor “A” No Communication | EV Diagnostics