When removing the engine oil filter from a 2002-2007 Suzuki Aerio, it is possible to contaminate the O2 sensor, causing DTCs P0137 (O2 sensor circuit low voltage/high voltage, sensor 2, Bank 1) (EVAP leak check model) and/or P0420 (catalyst system efficiency below threshold Bank 1). The oil can easily drip onto the downstream O2 sensor, resulting in internal contamination.
To prevent contamination, use a folded shop towel to cover the O2 sensor. Allow the engine to cool for a few minutes before servicing the engine oil and filter.
