Check Engine Light Due to Vacuum Leaks, Oxygen Sensor, or Catalytic Converter Fault on Audi A4

Problem Description and Possible Solution

Vacuum leaks, oxygen sensor failure, and catalytic converter efficiency faults can cause the Check Engine Light to illuminate.

Problem Data
RepairPal Verified
Average mileage: 99,757 (54,000–155,000)
Exhaust & Emissions affected: 1.8L 4 Cylinder Turbo
12 model years affected: 1997, 1998, 1999, 2000, more2001, 2002, 2003, 2004, 2005, 2006, 2010, 2012
36 people reported this problem
Viewing 1 - 6 of 6 comments
check engine light on
Catalytic converter is bad. :( must replace before next smog check.
Blinking engine light - diagnosis bad hoses, etc in need of immediate repair.
engine light came on, checked code and it read PO420 catalyctic converter maybe bad
Eratic turn signals
Crankcase breaker system was replaced to correct check engine light fault. Symptoms were: check engine light and rough idle.