OBD Guide
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B278C

Lost Communication With Power Source Control

B278C is an OBD-II diagnostic trouble code meaning: Lost Communication With Power Source Control. Common causes: broken or damaged wiring harness, poor contact in connectors. Estimated repair cost: $56–167.

Severity
🔴 High
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$56–167 (est.)

Symptoms

  • Unstable operation of electrical equipment
  • Periodic shutdown of systems
  • Malfunction indicator light comes on
  • Lost connection with diagnostic equipment

Causes

  • Broken or damaged wiring harness
  • Poor contact in connectors
  • Malfunction of the power control unit
  • Blown fuse
  • Short circuit in the circuit

How to Fix

  1. Check fuses associated with the power control system
  2. Inspect connectors and wiring harness for damage and oxidation
  3. Check the voltage on the power control unit
  4. Scan other modules for communication errors
  5. If necessary, replace the faulty unit or restore the integrity of the wiring

Related codes

U0100U0121B278D

FAQ

What does the B278C code mean?

B278C is an OBD-II diagnostic trouble code that indicates: Lost Communication With Power Source Control

What causes a B278C error code?

The most common causes of B278C include: Broken or damaged wiring harness; Poor contact in connectors; Malfunction of the power control unit; Blown fuse.

How do I fix a B278C diagnostic trouble code?

To fix B278C: Check fuses associated with the power control system. Inspect connectors and wiring harness for damage and oxidation. Check the voltage on the power control unit. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with B278C?

Limited driving only, diagnose soon

How much does it cost to fix B278C?

The estimated repair cost for B278C is $56–167. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat