Why might my "check engine" light still be on?

Question

I have a 2003 Accent that I haven't had any major problems with until this fall. The "check engine" light came on, brought it to a mechanic and one of the oxygen sensors and MAP sensor had to be replaced. A week later it came on again and the other oxygen sensor was replaced. A week later it came on AGAIN! I brought it to a different mechanic who told me the problem was something else because both oxygen sensors and MAP sensor wouldn't all go off at pretty much the same time. He determined a new computer was required so that was replaced. Guess what happened the following week? Yeah, so brought it back to the second mechanic, he brought it to the Hyundai dealership thinking the computer (which was previously used) had to be reset. That was last week, and it just turned on again today. I commute a fair distance and it seems to come on after 400 km of highway driving. Does anyone know what else it could be? I read that it could even possibly come down to faulty signals from the battery or alternator? During this whole time there hasn't actually been an issue with performance; it runs very well. I'm just sick of seeing the check engine light all the time. Any advice would be really appreciated!

Holey Mufflers · Accepted Answer

haven't touched this platform.
but there are a few things that baffle me.
codes pointing to sensors, don't automatically mean a bad sensor. they need to be tested. checked good, then the components or environment they monitor should be questioned.

generically, i can think of one thing that would cause an o2 (oxygen) and a MAP (manifold absolute pressure) to prompt a code. that's an intake leak of some sort. that may not be correct as it's a generic assessment.
those sensors monitor environments. that environment has a myriad of components that need to be in serviceable condition to maintain and environment that falls within the computers preset parameters.
someone familiar with this platform maybe able to help point you to the most likely issue.
until then all i can say is it sounds like the mechanics are not looking at the environment in question as a whole.

i know this is no solution. but someone is not doing their job right.
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EDIT,
respectfully,
IAC valves are testable. in this platform it's called an IAT-air intake temp. those procedures are found in every manual i have, and online manuals. for very vehicle i know of that uses one. that's 40+ years of wrenching. it's usually in emissions test section.
for instance, testing and removal info on all emissions components on an '03 accent, including the IAT, can be found here,
http://www.autozone.com/autozone/repairinfo/repairguide/repairGuideContent.jsp?pageId=0996b43f80378583
and a faulty IAT shouldn't, by itself, prompt a MAP code. o2 maybe. but not MAP. MAP is a vacuum pressure sensor. it doesn't care about temps and mixtures.
which when accompanied by an o2 code, smacks of a non-specific induction leak. not definitive-as again, not familiar with this specific platform.

Robert M · Answer

One item that is continually ignored is the IDLE AIR CONTROL VALVE. Most cars do NOT have a test for it's proper functioning. Some do, some don't. THe root of your problem is fluctuations in fuel/air ratio mixture, which the IAC valve controls by signals from the computer. When it gets clogged up by engine oil vapors, it stops moving and changes in the mixture cause sensor to flare up. ANSWER: Clean the living crap out of this valve with Gum-out and amsoil foaming cleaner if you can find it. Clean the throttle body and the PCV valve and hose. The number one culprit is the extended use of improper oil in the engine. Vapors are made and things clog up. It is as simple as that. SYNTHETIC oil is the answer after you have fixed the problem. No vapors are formed and things remain clean. $15 in cleaners should mend your woes. Your IAC valve should ALWAYS be showroom clean. It is the heart of your fuel mixture. And it will change your power and economy. Run these cleaners through you rintake system with engine running to clean off carbon from O2 sensors and even from converter. I neve rhave trouble with O2 sensors, because I keep my engines clean and the IAC valve immaculate. You should also change your plugs using denso IRIDIUIM or BOSCH Fusion plugs because they burn fuel chemically different than regular plugs There is probably NOTHING wrong with your computer. Power wash the engine and clean the valve, you should be FINE! E-mail me back with your results..

bajakma · Answer

When the check engine light comes on it saves a code, you need to find out what the code is for anyone to help you. Just out of curiosity does the light come on after you fill the tank with fuel? If so a bad gas cap can cause a fault code p0442 i believe. stop at an autozone they can pull the code for free.

Poul · Answer

agree with bajakma,
Find a service where will diagnose your computer and find the error code.
also it may be and from battery or fuel system... but first before try to do something find and read the error code. Do not waste time and money for nothing

bekis · Answer

To double verify the battery gentle, hook an decrease priced volt meter (multi-tester) to the battery with the truck working. The meter could examine between 13.5 - 14.0. volts. If the voltage would not fall interior that variety the alternator isn't charging the battery properly. Your community Ford broking is nice geared up to plug-in on your on-board pc to remedy the secret of the verify engine gentle. it may desire to be the catalytic converter, between the oxygen sensors, mass air pass sensor or grimy gas gadget. it is not extremely worth basically throwing factors on the truck devoid of understanding precisely what's incorrect.

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Why might my "check engine" light still be on?

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