Check Engine Light

Ok any advice would be so greatly appreciated here. We have a 2000 Ford Explorer with about 194,000 miles on it... and about a week ago we had it in the shop because the check engine light came on. They put in a new thermostat and all was fine. About two days later, the check engine light came on again. The only difference I notice when driving the vehicle is when I am at a stop sign and have my foot on the break it makes a very loud reving or grinding noise. The as soon as the light turns green and I take my foot off it stops and is fine. I thought maybe something was loose, but I really don't know where to begin looking. Any idea what this might be? Our biggest difficulty is diagnosing the problem.. once we figure out what it is we can fix it. This truck has been in the shop a few times over the past few months and I really can't afford to send it back right now. Thanks for all info, I really appreciate it! -Kasey

Welcome to the forum!

Since the check engine light (CEL) is on, you should be able to swing by a local auto parts store and ask them to read the codes. Most stores offer this as a free service. Try to get the actual code numbers and post back rather than the salesman's interpretation of what the code means.

Which engine does your Explorer have (4.0L, 4.0L SOHC, 5.0L V8)? If you shift to neutral when you are at the stop with the foot on the brake, is the noise still present? Does the engine seem to be running smoothly all the time?

-Rod