OBD Guide
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C1378

Capacitor Communication Circuit Malfunction

C1378 is an OBD-II diagnostic trouble code meaning: Capacitor Communication Circuit Malfunction. Common causes: open or short circuit in wiring harness, corrosion of contacts or connectors. Estimated repair cost: $56–167.

Severity
🔴 High
Can you drive?
Do not drive — repair immediately
Approx. repair cost
$56–167 (est.)

Symptoms

  • The security system malfunction lamp is on
  • Incorrect operation of airbags or pretensioners
  • Errors in other systems related to passive safety

Causes

  • Open or short circuit in wiring harness
  • Corrosion of contacts or connectors
  • Faulty capacitor
  • Problems with the security control module
  • Damage to the squibs in the system

How to Fix

  1. Check the wiring harness for damage
  2. Inspect connectors and contacts for corrosion
  3. Check the resistance of the capacitor coupling circuit
  4. Test the security control module
  5. If necessary, replace faulty components

Related codes

B0001B0020C1380

FAQ

What does the C1378 code mean?

C1378 is an OBD-II diagnostic trouble code that indicates: Capacitor Communication Circuit Malfunction

What causes a C1378 error code?

The most common causes of C1378 include: Open or short circuit in wiring harness; Corrosion of contacts or connectors; Faulty capacitor; Problems with the security control module.

How do I fix a C1378 diagnostic trouble code?

To fix C1378: Check the wiring harness for damage. Inspect connectors and contacts for corrosion. Check the resistance of the capacitor coupling circuit. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with C1378?

Do not drive — repair immediately

How much does it cost to fix C1378?

The estimated repair cost for C1378 is $56–167. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat