OBD Guide
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U121F

Audio and Video Control Unit Internal Communication

U121F is an OBD-II diagnostic trouble code meaning: Audio and Video Control Unit Internal Communication. Common causes: problems with the unit software, damage to internal module components. Estimated repair cost: $56–278.

Severity
⚠️ Medium
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$56–278 (est.)

Symptoms

  • Multimedia system does not work
  • No sound from the audio system
  • Glitches or screen freezes
  • No connection to navigation
  • Error message on display

Causes

  • Problems with the unit software
  • Damage to internal module components
  • Module power problems
  • Corrosion or oxidation of contacts
  • Wiring harness damage

How to Fix

  1. Check module connections and connectors
  2. Check the power supply and ground of the module
  3. Update module software
  4. Carry out CAN bus diagnostics
  5. Replace the audio-video unit if necessary

Related codes

U121EU1220U121D

FAQ

What does the U121F code mean?

U121F is an OBD-II diagnostic trouble code that indicates: Audio and Video Control Unit Internal Communication

What causes a U121F error code?

The most common causes of U121F include: Problems with the unit software; Damage to internal module components; Module power problems; Corrosion or oxidation of contacts.

How do I fix a U121F diagnostic trouble code?

To fix U121F: Check module connections and connectors. Check the power supply and ground of the module. Update module software. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with U121F?

Yes, but get it checked soon

How much does it cost to fix U121F?

The estimated repair cost for U121F is $56–278. Actual cost depends on your vehicle, location, and labor rates.

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