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Pete, Mercedes Mechanic
Category: Mercedes
Satisfied Customers: 24200
Experience:  Over 15 years experience as a Mercedes dealer technician
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Mercedes-Benz ML350 How do I reset the check engine light

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How do I reset the check engine light on a 2003 ML350. I went to repair shop and was charged 105.00 to get it reset three days ago and told that I needed to use Super Premium grade gasoline that if the light came back on after filling up with Premium grade gasoline he would reset for only 50.00. Can I reset it manually?
Hello,I will be glad to try and assist you with this,Welcome to Just Answer.


If the light came back on then this indicates a fault in the engine or transmission controlled components or system.

What needs to be done from here is to have the fault codes read out of the computers with a scan tool that can communicate with this vehicle or a dealers sds machine.Once the code has been read out it can be diagnosed as to what is at fault and what needs done to repair this problem.

It sounds like it was misdiagnosed the first time as the light shouldn't have come back on and usually fuel grade is not going to turn this light on.

The only way this can be cleared out is by using a scan tool,code reader or a dealers sds machine.There is no manual way of clearing the code and turning this light off.

Let me know if you need anything else,click accept if you feel satisfied with your answer as this is how I get credited for my time,Thanks Pete!
Customer: replied 5 years ago.
Mechanic said "Code 1" catalytic converters and that if I use premium gas it would be alright.
The catalytic converters are common to fail on this vehicle and using premium or upgraded fuel wont correct this problem here.

To correct this problem the catalytic converters or converter that is affected will need replaced and then the check engine light can be cleared out and the light will turn off.

This can cost anywhere form $1000 to $1700 depending on if one or both have failed.

Let me know if you need anything else,click accept if you feel satisfied with your answer as this is how I get credited for my time,Thanks Pete!
Pete and 3 other Mercedes Specialists are ready to help you
Customer: replied 5 years ago.
Can I purchase a scan tool to reset the light?
As long as it is made for European vehicles then this would work.Scan tools can be expensive though I would go for a code reader that will work with European vehicles these are much cheaper.They should say on the box/package if they will work on your vehicle.

If the fault isn't corrected though the light will eventually come back on.

Thanks Pete!