View source for 16804/P0420/001056

__FORCETOC__
=== 16804/P0420/001056 - Catalyst System; Bank 1: Efficiency Below Threshold ===

==== Possible Causes ====

* Oxygen Sensor(s) defective
* Oxygen Sensor(s) Control defective

==== Possible Solutions ====

* Check Oxygen Sensor(s)
* Check Oxygen Sensor(s) Control
* Perform Oxygen Sensor(s) Aging Check

==== Special Notes ====

* For 1.8T's experiencing this fault code, this thread may be useful: http://forums.vwvortex.com/zerothread?id=663057

[[Category:Fault Codes]]