Q: My car is reading a code die evaporative emission system leak. But when I accelerate to 70 it will not speed up

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My check engine light is on and the code that it's reading is po442 emission small leak. But when I accelerate on the freeway and I hit 70 it won't accelerate past 70 and my check engine light flashes. I believe these might be two separate issues the one I'm concerned about is acceleration.

My car has 204000 miles.
My car has an automatic transmission.

The flashing check engine light signifies misfiring and the engine fault(s) causing the misfiring are probably related to the loss of power you are describing. Misfiring is potentially very damaging and so you should drive at a lower speed to keep the check engine light from flashing and also have the necessary diagnostic and repairs performed as soon as possible. If you request a misfiring diagnostic the responding certified mechanic will get this diagnosed and resolved for you, right at your location. Common causes of cylinder misfiring are faulty spark plugs, low compression, damage or excessive wear of spark plug wires and/or coils, faulty fuel injector, clogged EGR valves or tubes, burned valves, improper ignition timing, vacuum leaks, leaking head gasket, faulty camshaft sensor, faulty crankshaft sensor, faulty mass air flow sensor, faulty oxygen sensor, faulty throttle position sensor, faulty catalytic converter, and others.


With regard to Diagnostic Trouble Code P0442, a loose or defective gas cap is one possible reason that the code has set. You could also have a leak in the EVAP system. The most common fault though is a loose or defective gas cap and so initially you should check the rubber o-ring seal on the cap, as well as the mating area on the filler pipe, for dirt, irregularities, or other defects that might be preventing the cap from properly sealing at the filler tube. Clean or address any problems you see as needed and then re-apply the cap. Erase the stored code. If the code returns, the mechanic who resolves the engine misfiring, which as noted is critical to resolve right away, will also diagnose and resolve this EVAP code for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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