OBD Guide

P0491

AIR System Insufficient Flow Bank 1

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

Symptoms

  • Increased emissions
  • Unstable engine operation at idle
  • Check Engine light comes on

Causes

  • Clogged air channels of the secondary air system
  • Secondary air system valve malfunction
  • Problems with the secondary air pump
  • Open or short circuit in wiring harness
  • Air pressure sensor malfunction

How to Fix

  1. Check the condition of the air channels of the secondary air system
  2. Check the operation of the secondary air system valve
  3. Check the secondary air system pump
  4. Check wiring harness for damage
  5. Check air pressure sensor

Related codes

Error P0491 by Vehicle Brand