Question'95 Taurus Wagon, not SHO, 148,000 miles,
engine warning light will come on periodically. Will not be on during short trips. Usually about 4 miles into a drive. Especially at high rpm.
It will turn off at times. thanks
AnswerSteve, you'll need to start with a diagnostic 'code check' by someone having a scan tool. This will give you the code set whenever that 'check engine' warning lamp came on recently. (the code will be stored for several restarts after the problem occurred)
Once you know the system to investigate, several pinpoint tests will locate the problem. It could be a wiring connection, a failed sensor, or a failed component that a properly functioning sensor can detect the result of.
That is where a Ford-trained technician earns his money. If the code, for example, is a P0401 - DPFE voltage higher/lower than expected - that doesn't mean the DPFE sensor is bad. It might be, but it might be reading the lack of EGR from a failed EGR valve, or the lack of EGR from a good valve that has too much carbon deposits to allow proper flow through the ports.
You'll need some real test performed, and your Ford dealer is probably your best bet to get it right the first time.
Hold them to it! If they offer a solution and a price for that, decide if the repair is something you can do, or rather allow them to do it. If they do the repair and the light comes back on, expect them to make it right and continue diagnosis without additional charge. Of course, if you (or someone else) does the repair, you can't expect the dealer to retest their work at no charge. That's what most customers expect from the professionals!
Hope this helps,
Clay
