Check engine light

I have 99 1.8t passat and sometimes check engine light comes up. Also, i noticed a little lack of power on acceleration sometimes too; perhaps it could be due to cold weather. I am thinking that it could be oxygen sensor. Any inputs are greatly appreciated.

Get the trouble codes read, most Advance Auto or Autozone type chains can do it for free.

Thanks for reply. It seems like the connector for the computer is malfunctioning, saying something about communication fault. Any ideas?

Thanks for reply. It seems like the connector for the computer is malfunctioning, saying something about communication fault. Any ideas?

I am new to this forum. A loose gas cap (cap not tightened until it clicks) will cause the Check Engine Light to come on. A scan by AutoZone or Advanced Auto will read "small leak". The light will go off once the cap is tightened and you drive the Passat a while (1 1/2 days for me).