2018 E300 check engine light came on
I put my car on jack stands and removed all four wheels, then I started the engine and run it for a while. After I reinstalled all wheels and had a test drive, I noticed the check engine warning staying ON. I am wondering if Running the engine when the car on jack stands damages the engine? Please help!

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Thank you for your reply!
I run the engine with the car on jack stands so the brake rotors can spin then I can use a die grinder to remove the rotor raised edges. Actually it triggered few warnings such as parking brake, ABS etc, also caused the engine cooling fans running crazy, but other warning cleared except engine warning after test drive.

Anyway, very good that the light went off, hope it stays off.
My blue tooth ODB code reader does not work on 2018E300, I need to buy a new one.I ran the engine at idle speed for about 20 minutes and the radiator fan was turned on and ran very loud. After I turned off the engine, the fan still ran for very long time, then I hold the start button for few seconds to turn off it. This may triggered the check engine warning?
I run the engine with the car on jack stands so the brake rotors can spin then I can use a die grinder to remove the rotor raised edges. Actually it triggered few warnings such as parking brake, ABS etc, also caused the engine cooling fans running crazy, but other warning cleared except engine warning after test drive.
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As for the thermostat, I suppose before it could have been too hot because you're not getting air circulation with the engine running and the low temperature is probably just a bad thermostat now.
As for the thermostat, I suppose before it could have been too hot because you're not getting air circulation with the engine running and the low temperature is probably just a bad thermostat now.





Happened on my old E63, thermostat replaced under warranty. CEL came on, and I noticed temp gauge was only half way up instead of 2/3 way up after freeway driving.
Last edited by taphil; Sep 15, 2023 at 10:59 PM.
Happened on my old E63, thermostat replaced under warranty. CEL came on, and I noticed temp gauge was only half way up instead of 2/3 way up after freeway driving.
Hi, thanks for your reply. What's the actual temperature when your temp gauge was 2/3up? My coolant temp gauge reading stays at 90 degrees celsius.

Everything seems normal now. I think the thermostat is fine. hope it doesn't come back.





