Service engine light
 

I realize this has been beat to death but I could use a refresher course. My 98K mile 2004 525i just passed inspection in March but two weeks ago my service engine light came on so I checked the i-log and found a message that my emissions have increased. I believe this is due to having never changed the spark plugs (I may have the OE plugs still in the engine) but I can not say for sure.


I have tried resetting/turning off the light without success, coach me through the process/steps again please.


Gregg


PS, The car still purrs like a kitten but I have noticed a decrease in mpg. Will be changing spark plugs this weekend.

Spark plugs are probably not the reason for MIL. You cannot just turn off the light and expect all to be well. You need to read the fault code (or have someone do it for you) and correct the cause of the fault whatever it may be. Only then will the light remain off. At 98k miles, plugs are due for replacement, but don't expect a miraculous transformation.

Care to elaborate?

When it is time for a spark change the icon will show for it. Your MIL is for issues with the car that are not regular maintenance items. So if your MIL (check engine light) is on or messages stored in your "i-log" that means there is something wrong with the car and the error code needs to be read to troubleshoot the issue. Increased emission error could be anything (spark and or wires, injectors, vacuum, gas cap/bad gas, blocked air filter, catalytic converter, mass airflow sensor and so on). If you do not know the code you do not know where to start with fixing the car.

Where is that thread with the directions to reset the service light? I have reset in before but that was over 2yrs ago, I can get to the triangle with ! mark but cannot progress past the brake fluid image and reset.