Car is an 03 Z06 36k miles. Started with the no start. You turn key and nothing. All power works, just no start. When the car would start i get security light, and p1631 and b2721 pass key codes. I got a new key from Chevy that worked for a while. Car did it again. I bought a new lock cylinder...still the same. Swapped out my battery for a new one. Soon as i put new battery in yesterday...no start. Now today I go out and the car fires right up. I leave it run for 25 min. Shut it off and turn it on 5-6 times and it starts everytime with no codes. I am going to drive the car and i'm sure i'll get the security light. It seems to take about 5 miles of driving for the light to come on. I have read threads until im blue in the face. Is it possible that the new battery and lock tumbler took a little while for computer to learn the new lock cylinder? Whats my next step here. Bypass the vats altogether? I cannot use a multimeter by the way, and i have no problem not having this junk VATS system on my car if it will rid me of these problems. I plan to sell the car soon and want the issue taken care of for the new owner.....

One other question....while wiping the motor down today I noticed a sensor plug in that didn't have the male end plugged in up by the front bumper by air intake. My air intake is homemade and I will be getting a better one as there is one of my AIR tubes on the opposite side of this sensor im talking about that isn't plugged in either and throws a engine light sometimes....anyway heres a pic of the sensor. What is it?



and heres a pic of my intake

 

any input would be great guys,

I drove the car around this evening and it started every single time. However, after 5-8 miles i get the security light staying on. WHen i shut the car down the light goes off and it re starts fine (security light goes off as it should when i turn key to 'on' position). i am getting the b2721 H code. Didn't see the p1631 code.

 

The code with the "H" ending means it's just a history code showing that at one time that code was thrown. It takes 50 on-ff cycles without a repeat for the code to go away. You can clear the code yourself by holding the options button down and pressing fuel 4x. Once you've done that it will go through all the modules for codes. It will then enter the manual mode and you can cycle through that and clear the code yourself. I don't recall right off hand which buttons do which in the manual mode but the E/M button will exit you out of the manual mode. Two of the buttons will move you up and down through the different modules and the third will clear the code history when held for 2 seconds.

Someone help me out here which buttons do which, don't have access to that stuff right this second.

 

Yes, I know how to read/clear the codes. I am still getting the security light, the 2721 is showing as a history code. However, I assume the security light being on means something is still wrong. I am happy it started every time today. Just curious what my next move should be. Should I wait it out a few more days, and keep driving the car hoping the light stops coming on? Is there a learn procedure once you put in a new lock cylinder and key that would make the security light come on yet not throw a current code.?

P.S anybody know what that sensor is in the first pic?

 

bump

anyone???