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Q: Will not go faster than 35 mph, emission light on also on 2005 Mercury Mariner

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.
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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.

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