The emission light has been on for a while, then one day, was at highway speed, slowed to 35 mph an would not go faster.
Mercury Q&AAsk Your Question
2005 Mercury Mariner Question: Will not go faster than 35 mph, emission light on also
Answer #1mastertech6371 November 18, 2011, 10:27Master
have the cat converter check for back pressure failure and have the fuel pressure checked.
this is why it is an issue with leaving on the check engine light for a long period of time. we always recommend repairing the car when the light comes on as more damage may result not attending to it at the time of failure.