OBD Guide

P0418

AIR System Control A Circuit

P0418 is an OBD-II diagnostic trouble code meaning: AIR System Control A Circuit. Common causes: secondary air system solenoid valve malfunction, open or shorted wiring harness. Estimated repair cost: $33–167.

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$33–167 (est.)

Symptoms

  • Check Engine Light Is On
  • Deterioration in acceleration dynamics
  • Increased fuel consumption
  • Unstable engine operation at idle

Causes

  • Secondary air system solenoid valve malfunction
  • Open or shorted wiring harness
  • System relay malfunction
  • Problems with the engine control unit (ECU)
  • Mechanical damage to system components

How to Fix

  1. Check the integrity of the wiring harness and connections
  2. Test the functionality of the solenoid valve
  3. Check the secondary air system relay
  4. If necessary, replace faulty components
  5. Reset the error code and check if it returns

Related codes

Error P0418 by Vehicle Brand

FAQ

What does the P0418 code mean?

P0418 is an OBD-II diagnostic trouble code that indicates: AIR System Control A Circuit

What causes a P0418 error code?

The most common causes of P0418 include: Secondary air system solenoid valve malfunction; Open or shorted wiring harness; System relay malfunction; Problems with the engine control unit (ECU).

How do I fix a P0418 diagnostic trouble code?

To fix P0418: Check the integrity of the wiring harness and connections. Test the functionality of the solenoid valve. Check the secondary air system relay. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P0418?

Limited driving only, diagnose soon

How much does it cost to fix P0418?

The estimated repair cost for P0418 is $33–167. Actual cost depends on your vehicle, location, and labor rates.

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