16805/P0421/001057

From Ross-Tech Wiki

16805/P0421/001057 - Warm Up Catalyst; Bank 1: Efficiency Below Threshold

Possible Causes

  • Warm Up Catalyst Bank 1 faulty

Possible Solutions

  • Check Warm Up Catalyst Bank 1
    • Set Readiness
  • Replace Warm Up Catalyst Bank 1

Special Notes

  • When found on the following, there may be a firmware update:
    • 2000 - 2001 Passat with ATQ engine, see TSB 01-07-07 (TPI 2010372)
    • 2000 - 2001 A4 or A6 with ATQ engine, see TSB 26-08-07 (TPI 2013086)
    • 2001 Allroad with APB engine, see TSB 01-08-20 (TPI 2005579)
    • 2001 A4 or A6 with APB engine, see TSB 01-08-34 (TPI 2012357)