I have heard that having the SES light on will cause the fans to come on. Have also heard some say that programing is changed while the SES light is on.

Will having the SES light on make the computer revert to a default(safe-limp home) programing?
i.e. ignoring the programing I added using a HPP III to correct my speedo for 4.10 gears.

I have had people tell me I am going faster than I thought I was going, so either the computer has ignored the HPP III programing or I don't really have 4.10 gears.

Any help is appreciated because I am lazy and don't feel like taking the rear end cover off to count gear teeth.

 

An SES will cause the fans to come on, but the computer will not ignore the changes made by your Hypertech.

 

Thanks, time to count some gear teeth.

 

It depends on what the SES light is for, some things are not critical, it could be an exaust leak that causes a false lean condition and SES light - but it wont put you in open loop.

 

The current SES code that I have is for my EGR valve. I also must have a exhaust leak somewhere because I can hear it but I think it is where my y-pipe slips into my cat back exhaust.

 

If its all the way back at the Y pipe to catback flange, its not going to affect the O2s. If its at the manifold where it meets the Y on a stock type setup, it will effect the drivers side O2, if its where the manifold meets the head it will effect whichever side its on.