OBD Guide
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U1A4C

Build/End Of Line Mode Active

U1A4C is an OBD-II diagnostic trouble code meaning: Build/End Of Line Mode Active. Common causes: undisabled factory mode after assembly, incorrect ecu programming. Estimated repair cost: ~$167.

Severity
🔴 High
Can you drive?
Yes, but get it checked soon
Approx. repair cost
~$167 (est.)

Symptoms

  • Check Engine Light on Dashboard
  • Limitation of functionality of vehicle systems
  • Inability to pass OBD-II diagnostics
  • Unusual behavior of electronic systems

Causes

  • Undisabled factory mode after assembly
  • Incorrect ECU programming
  • ECU software failure
  • Attempted tampering
  • ECU memory damage

How to Fix

  1. Diagnostics using a professional scanner
  2. Flashing the ECU
  3. Reset ECU adaptations
  4. Software integrity check
  5. Contacting an authorized service center

Related codes

U1A00U1A0D

FAQ

What does the U1A4C code mean?

U1A4C is an OBD-II diagnostic trouble code that indicates: Build/End Of Line Mode Active

What causes a U1A4C error code?

The most common causes of U1A4C include: Undisabled factory mode after assembly; Incorrect ECU programming; ECU software failure; Attempted tampering.

How do I fix a U1A4C diagnostic trouble code?

To fix U1A4C: Diagnostics using a professional scanner. Flashing the ECU. Reset ECU adaptations. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with U1A4C?

Yes, but get it checked soon

How much does it cost to fix U1A4C?

The estimated repair cost for U1A4C is ~$167. Actual cost depends on your vehicle, location, and labor rates.

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