1999 Mercury Tracer LS started with check oil light. Serviced at Shell. Car began to backfire and lose power. Diagnosis at Shell who recommend changing plugs and wiring. After 5 min of driving, same symptoms. Back and forth to the mechanic who replaced the air intake valve, radiator, oil and filter because check engine light started to come on. So far 30 days trying to fix. Given the all clear yesterday and drove off. Next day check engine warning light comes on. FIXD code P1506 Idle Air Control Overspeed Error. Have lost confidence in Shell Mechanics. What can I do?
What can I do?
The car is 25 years old and past its expected service life, so it could be developing any number of issues. As far as the P1506 code is concerned, it appears you have a problem with your IAC valve or its circuitry. If unable to diagnose and repair it yourself you need to find a better mechanic who will actually diagnose the problem instead of guessing.
There's plenty of information you can find online via a web search, for example:
https://www.autocodes.com/p1506_ford.html
https://www.youtube.com/watch?v=b3rYjScQKYE
https://www.youtube.com/watch?v=Y7gEuz8Y-gw
What can I do?
Find a good independent mechanic and stop going to chain shops.
