Evap cntrl system pressure señor low?will that macke your truck not run

It likely won't prevent your truck from running. Check/replace the gas cap--the O-ring may have deteriorated. Then, reset the ECM with a code reader.

I have a 2004 chevy silverado that won't start. And its got a code 4 evap. Control system pres señor. How can I change it.

Have you tried replacing your gas cap? The O-ring may have deteriorated and gas is escaping, which the sensor senses. I doubt a Code 4 would prevent the truck from starting.

Instead, focus on the tests below:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-11.html#post2123675