89 560SEL Trouble code on/off ratio
 

I have 30% reading on my '89 560SEL. I know its regarding the coolant temp sensor or wiring. I have replaced sensor, and the resistance values both come to the EZL and ECU, meaning the wiring is ok. But the code still remains.

How do I clear the 30% reading? I have disconnected the ECU, Battery, OVP relay but the I still have the code.

Unfortunately sometimes there is nothing wron with the system, but the ECU continues to generate codes. I went through this about a year ago with a 90 300SEL. I kept getting several codes. I checked the system thorougly and had to replace the ECU to get rid of some of the codes. I then had to replace the MAS unit to clear the rest of the codes. I'm at home now so I don't have my books. I'll look your system up later today.

Thanks for the reply. I guess I should have been more specific with the code.
It is actually a ON/OFF frequency reading, shown as a percentage of duty cycle, typical of K-Jets.
According to the book, this can be done with the tester, but I dont have one.

Well, this is an OLD question, but...

You cannot "clear" the duty cycle codes. They are not stored because they are a Real Time measurement.

Here's a handy link for KE-Jet