OBD Guide
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C1311

Open In Main Relay 1 Circuit

C1311 is an OBD-II diagnostic trouble code meaning: Open In Main Relay 1 Circuit. Common causes: faulty main relay, broken or damaged wiring harness. Estimated repair cost: $11–111.

Severity
🚨 Critical
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$11–111 (est.)

Symptoms

  • Engine won't start
  • Power Loss
  • Check Engine Light Is On
  • Unstable engine operation

Causes

  • Faulty main relay
  • Broken or damaged wiring harness
  • Corroded or oxidized contacts
  • Blown fuse
  • Engine control unit (ECU) malfunction

How to Fix

  1. Check the condition of the main relay fuse
  2. Test the main relay (replace with a known good one)
  3. Check the integrity of the wiring harness between the relay and the ECU
  4. Clean the connector contacts
  5. If necessary, replace the relay or repair the wiring harness

Related codes

P0685P0686P0687

FAQ

What does the C1311 code mean?

C1311 is an OBD-II diagnostic trouble code that indicates: Open In Main Relay 1 Circuit

What causes a C1311 error code?

The most common causes of C1311 include: Faulty main relay; Broken or damaged wiring harness; Corroded or oxidized contacts; Blown fuse.

How do I fix a C1311 diagnostic trouble code?

To fix C1311: Check the condition of the main relay fuse. Test the main relay (replace with a known good one). Check the integrity of the wiring harness between the relay and the ECU. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with C1311?

Yes, but get it checked soon

How much does it cost to fix C1311?

The estimated repair cost for C1311 is $11–111. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat