Quote:
Originally Posted by ard
THERE ARE 100 THINGS THAT CAN TRIGGER THIS LIGHT!!!!!! The "light" isn't the "Fault" or "problem"... there is an underlying failure that triggered it. To say "I have this light too" is to not understand the function of a "Check Engine Warning Light" You need to find out the actual CODE that tripped the light to get at the fault- the dealers love customers that don't ask questions....the sensors don't get 'confused' and if they do, they are defective.
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Yup. And, as you know, the code cannot be taken at face value. A perfect example is the DPFE (Differential Pressure Feedback EGR) sensor on the Ford Focus. To determine if the EGR valve is working, Ford has a sensor which measures the pressure differential across the EGR valve. If the computer, via the DPFE sensor information, determines the EGR Vale is not working, it will throw a CEL (check engine light) and a code which indicates the EGR valve is defective. So, many people take the code at face value and replace the EGR Valve, only to still have the CEL and the same code -- 9 times out of 10 the EGR valve is just fine, but the DPFE sensore has failed. On the Ford Focus, this is a not uncommon cause of getting a CEL.
You would hope that the dealer's mechanics would know all of this, but too many dealerships have some young mechanics that tend to take the codes at face value and throw parts at it.