I heard there could be tremendous gains from changing the knock sensor.

Should i wait for the "check engine" light to come on to change my knock sensor or should i just change it? I just bought my 1996 GLE 3 months ago and it has about 140,000 miles on it currently.

 

The check engine light wont come on with the knock sensor
You have to check the ecu

 

I thought you only check the ECU when the "check engine" light comes on.
Is that right?

 

No. That is not right. The knock sensor (and possibly others...I really don't know) does not turn on the light. It will however throw a code. If bad replacing will make a big difference. Don't just replace it for no reason though.

 

Isn't it only emission related failures that trigger the CEL???

drew

 

No.
10char.

 

thanx for the help

 

when the ignition is in on position (engine not running) is the check engine light always supposed to go on then go off when engine turns on? Because min does not come on at all.

 

does it really help that much?

 

If it's bad it does.

 

i felt the difference when changed, plus it hurts ya gas