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)