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Check Engine Light – Concern, Cause and Correction

Written by maryp posted on Wednesday, February 26th, 2014

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diagnosticsYou may not realize it, but there are over 600 items that could trigger your check engine light to illuminate. It can be a simple fix.  However, in some instances, it may also be complex to get to the cause and correction.

The mystery of diagnosing your check engine light is one that is not easily understood by many vehicle owners. The commercials running non-stop or popping up on your screen are not helping to educate anyone, either.

When the actor posing as a tech says something like, “…it’s only a simple solenoid…”, it sounds so quick, simple and inexpensive.  In the case of this “solenoid”, nothing could be further from the truth. Just because you have a fault code (also referred to as a trouble code) that reads out on a tool does not mean that is the definite answer.

A tech plugged in a tool and what did it tell him? The fault did not tell him if it was a corrupted control unit, faulty wiring, a connector, or a possible problem with a wiring harness. He sees fault code, yes, but did he check for TSB’s checking for a technical update?  What if he did none of the checks and just installed new solenoid and the problem still exists?  He then has to “baseline” the car, and now he discovers that there is high voltage entering the system from a defective diode in the alternator!

In this particular “solenoid” example, there is only a 1 out of 6 chance that the “fault code” showing a solenoid is the real problem.  Unless that tech went further other than just “plugging in” it’s just a guess. The code did give him or her a starting point, but just that–a starting point.

The perception that a tech can now just “plug in a tool or plug in a  computer” and get a fix for your car with its 40 to 60 control units, is just not accurate.  When there is a need for diagnostics of your fine German auto, (AUDI BMW, Mercedes, or MINI), there should be a definite testing protocol that is followed to get you the best result with accurate information.  You do not want someone just changing parts till something fixes “it”.   Then it is a guess–not a repair. To expect that repairs are simple and cheap using today’s current technology is just not realistic for both the consumer and your local repair shop.

It takes training, experience, and OE technical information (paid for by your repair specialist)  to determine if further testing is required.  To understand the cause, is to determine the correction and that is what a good technician will do for you.

Another note:  those hand-held scan tools that are being advertised online for less than a few hundred dollars?  Do not waste your money.  The commercial versions of those tools are costing your local repair shop thousands of dollars.  There is no comparison.  In some situations, after the correct repair is made, the control unit has to be upgraded to the latest software program so that your sensors will “speak” to one another to complete the repair.  Your online code reader will not help with that, either.

It is a fairly regular occurrence that a person calls us wondering what could have gone wrong– they used their home code reader, changed a suspect part and are still facing the mystery of that darn check engine light. Don’t try this at home!

We will be glad to help you with your check engine light. We have helped thousands of German auto drivers for over 32 years.  Let us help you.

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