My car is reading a code die evaporative emission system ...

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

asked by on March 08, 2018

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.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

What is the average cost for a valve and piston rod replacement job. I thought it was the lifter but now they say its valve.

The cost depends on the amount of damage and is quite literally impossible to even guess at without physically removing the parts and determing exactly what parts have to be replaced. It is not just a simple matter of taking...

Knocking noise - 1997 Oldsmobile 98

Hi! I recommend having a close inspection of the harmonic balancer on the front of the crankshaft. When the rubber that's bonded between the pulley and the hub begins to fail and separate, it starts to move around and can...

My car won't turn on

The first thing to try is to put in new batteries in the key FOB and see if this helps. If it does then replace batteries in all extra keys also. If it still has issues then you may have...

Related articles

How to Get Buick Dealership Certified
GM/Buick car dealerships offer automotive technician jobs to mechanics who are certified through the Universal Technical Institute (UTI) and GM.
A Buyer’s Guide to the 2012 Buick Verano
The The 2012 Buick Verano is a near luxury sedan that is affordably priced with lots of technology and comfort that comes standard. The interior is covered in leather with a rich variety of colors. The legroom in the front...
The Best Used Cars to Buy for Towing Light Loads
Towing Towing is tricky business and depending on the weight you’re dealing with, it really determines what vehicle is best for you. If it’s light loads you’re looking at towing, we’ve put together a list of the top five cars...