OBD Guide
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U121A

Hard Disk Drive Write Malfunction

U121A is an OBD-II diagnostic trouble code meaning: Hard Disk Drive Write Malfunction. Common causes: hard drive damage, file system errors. Estimated repair cost: $56–167.

Severity
⚠️ Medium
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$56–167 (est.)

Symptoms

  • Malfunctions of the multimedia system
  • Losing saved settings
  • Navigation is slow
  • Error messages when saving data

Causes

  • Hard drive damage
  • File system errors
  • Drive power problems
  • Hard drive overheating
  • System software errors

How to Fix

  1. Check connections and power to the hard drive
  2. Run disk surface diagnostics
  3. Try restoring the file system
  4. Replace the hard drive if necessary
  5. Update system software

Related codes

U121BU121C

FAQ

What does the U121A code mean?

U121A is an OBD-II diagnostic trouble code that indicates: Hard Disk Drive Write Malfunction

What causes a U121A error code?

The most common causes of U121A include: Hard drive damage; File system errors; Drive power problems; Hard drive overheating.

How do I fix a U121A diagnostic trouble code?

To fix U121A: Check connections and power to the hard drive. Run disk surface diagnostics. Try restoring the file system. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with U121A?

Yes, but get it checked soon

How much does it cost to fix U121A?

The estimated repair cost for U121A is $56–167. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat