Can water in fuel cause P0300

Question

Can water in the fuel cause P0300 in Pentastar 3.6 V6? I started getting P0300 and rough running/hesitation. Noticed that when I put in a fresh tankful, it ran better for a while but is starting to act up again. Thinking that a slug of water would certainly cause a misfire. When misfire happens, O2 sensor voltage goes full scale, short term fuel trim and sometimes long term fuel trim go wonky, catalytic converter temperatures soar. Worst case, the fuel system goes open loop for a minute or two.

Answer 1

Hi there,

The answer is yes, water in the fuel is a very common cause of the multiple misfire code. This will also change the o2 sensor readings pretty dramatically when it happens.