I bought my 2015 Crystal Red Stingray with under 6000 miles last month and ended up needing work on the left fuel tank flange and pump right away. Fortunately I bought it at a Chevy dealer and they took care of the whole thing at no charge to me.

So I needed to get the car E-check'd in order to transfer my license plates, but they flagged me for the Evap sensor not being ready. Of course the dealer just had the battery disconnected and serviced the fuel system. I read up on Evap sensors and learned that on GM cars they are notorious for taking many miles and often several tanks of gas before they reset. Of course, if you read online you'll learn that you must have between 1/4 and 3/4 tank of fuel, cold start, and drive at various speed and time parameters to bring the various emission control sensors to a ready state.

I was two tanks of fuel into this process and the Evap sensor just wouldn't get ready for me. I bought a Scotty Kilmer recommended cheap scan tool which showed me that the Evap system was maintaining the specified negative pressures and there were no trouble codes, but the sensor wouldn't register as ready. As I reviewed the driving parameters, it seemed that a long decel from 55 mph to 20 without down shuft or touching the brake pedal was closely associated with the Evap self test.

I went out where I could find 15+ miles of divided highway and started running from one end to the other with the cruise control on at 55 and watching and waiting for long clearances in the traffic behind when I could release the cruise control and ride her down to under 20 mph (not easy to do without becoming a nuisance or safety hazard to other drivers). I found that on even a slight downhill decline, the car will idle at over 20 mph, so choosing a slight uphill incline area helps.

Anyway, I got at least a couple good uninterrupted 55mph to under 20 mph decelerations in and then went and idled for a bit and shut down. This is supposed to trigger the onboard computer to do some sort of self analysis regimen. I started the car up after 5 minutes, and plugged in my scan tool - the holdout Evap sensor was now ready for e-check!

Btw, I have read that some state smog check rules allow a pass with one sensor not ready, but Ohio does not. I was worried that I wouldn't get this done before I store the car for the winter, but I am excited that I can now go finish the registration and get my permanent plates on.

For the TLDR crowd; the long deceleration from 55 to 20 without braking or downshifting is the key to getting a lingering unready Evap sensor to reset.

 

Great info. I've been through the ringer on the sensors ready status too. The lesson is do not lose power from a dead battery because getting all the sensors back to ready on this car can be a bitch if you are close to an inspection. Took me a couple tanks too. If you google "Completing a Drive Cycle" you can get other good info. In my experience a cheap ODBII reader is worth it to make sure it will pass.

p.s. Texas allows one Not Ready code.

 

Glad you passed! VA also allows one not ready sensor. I ended up going out at 430 in the morning to get some of the recommended driving cycles complete. Had no idea this was even a thing until I failed emissions after a new battery.

 

Thank God I live in Florida and would t have to deal with that headache