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Check engine light

The idle air control in my '04 Subaru Impreza keeps turning on the check engine light. Lately, the engine stalls after about two minutes. A dealer’s service department tried replacing the IAC, but that had no effect; then the mechanic there tightened a connection pin on the engine connection. That had no effect. Next Ill have a relay replaced. The alternative is something–E. C. M., I think–much more expensive.

The check engine light comes on when I shift down, and it usually goes off after I drive 10 or so miles and park for half an hour or longer.

What are the likeliest causes for the above misbehavior? Am I risking my life for a mechanic’s enlightenment?



What risk of life? It’s a fixable engine problem.
What code? I don’t see a code? Let us know the code. We have our own decoder ring.
There may be a problem with the idle air control valve (iacv) wiring; but, we don’t know without the DTC code. DTC stands for Diagnostic Trouble Code. Notice the word: Diagnostic.
The iacv wiring should be checked for the appropriate voltage and ohm values. A proficient mechanic knows how to do that.

The code that keeps coming up is 519.
The fixes that have been tried are turn it off–it comes back; clean the IAC–the check engine light comes back;replace the IAC–the check engine light comes back with the same code, 519; tighten a pin on the engine connection; the check engine light comes back on. The next step will be replacing a relay.

The risk to my life is having the check engine light go on where I cannot safely pull over and restart the engine.


Is the “danger part”, the time the engine stalls after the check engine light comes on? Then, you have to quickly find a place to safely pull over, right?
This problem seems to be beyond the abilities of the dealer’s mechanics. You need to search for another shop which can handle these kinds of problems. Be willing to pay for some diagnostic time. This problem could take some time, and no body wants to work for free (or, close to that).

Thank you.