Check Engine Light went on on my S40 2004.
I pulled the code and it was infamous P0128.
I think that it was caused by my low coolant level.
I added the antifreeze but the light is still on.

I would like to reset it to see if it returns, and if so I would replace the thermostat and the sensor.

So here is the question: Can I reset CIL by disconnecting battery or removing some fuse?
Or it can only be done with the scanner / reset tool?
I am unable to find definitive answer anywhere....

 

Read the second post: https://volvoforums.com/m_64118/tm.htm
It can also be reset by pulling the main fuse.

 

TIPSP,
The link you kindly pointed me to refers to "Service" light reset procedure.
I reset this one a few times in the past and I am well aware of it.

This time I would like to reset "Check engine" light. The one just next to the "Service".
I hope I fixed the problem that caused it, but I can't be sure until "Check engine" is reset.

Disconnecting the battery didn't work for me, so if there is some other way to do it please share it.

 

I would reset it with a scanner.

 

you received that code because your tstat sensor is shot...this is very very common...buy a new sensor and tstat...install takes less than a half hour.

 

Thank you Tech. This is exactly what I have done.
My friendly mechanic reset it for me...

All is well now, and if the error returns I will do what mcguij1 suggested.

Thank you all.

So, is there any way other than the scanner to reset "Check Engine" in Volvo S40?
If it can't be done, which scanner should I buy and where?

 

if the cel came up for 0128, the problem won't go away, i just dont want you to be disappointed when it comes back on...from time to time the light will even go away on its own without reseting, but it eventually comes back...let me know the outcome!

 

You were right. It was running fine for two weeks and then the check engine light returned.
Today I replaced thermostat and the sensor.