Engin Light We just bought a 2006 Chevy Cobalt. The engine light came on then after driving a few miles went out. next day I was out driving it came on again. so I went to auto store to have code pulled . they plugged in tester and said the plug in my car must have a blown fuse or something because the tester couldn't get anything. as if car was off. How can I find out what is wrong if tester wont read

If the oil level (checked with the dipstick) is VERY high, and the oi on the dipstick looks like chocolate milk (or just after running, foamy chocolate milk), this usually means either the head gasket is blown, or the cylinder head or the engine block is cracked, allowing the engine coolant to mix with the engine oil.

Sounds like your crankshaft sensor is bad. It will stop working if bad and will leave you stranded. GOod luck.

Run a Diagnostic test on the vehicle computer,
code(s) stored in the vehicles PCM/ECM, will let us know more about the vehicles symptoms.
AutoZone will connect a scanner for free.
Post back with the codes

The light being on has probably put the car in "limp in" mode. Its a kind of fail safe system to allow car to be driven to a shop for repairs. You need to have the code or codes read by scanning the engine computer, repair the problem, erase the codes, and then you should be able to drive it again normally.

You have a leak. Check the oil to see if there is water in it. Withe the engine running, check the tailpipe to see if excess water is coming out. If yes to either of these, then you have a bad head gasket or cracks in the head/block. You need to find where the coolant is leaking in order to fix it.

I had this problem as well. Took it to the garage and it was a $700 bill the part alone was $440 they had to drop the gas tank - and since then it's not been working right. The fan clutch went a week later another $700 bill. Picked it up and it was still making the same sound - garage replaced another sensor without charging me--picked it up and three days later the service engine light came on. Back to garage and another $80 part was needed under the hood. All this with just 52,500 miles and I keep it well maintained. Not a happy camper at all! Holding my breath but it's been only two days so far so good.

Number three cylinder is miss fire,it does not mean it is the coil,although it could be,remove the coil,and boot,and spark plug,inspect them to see if the plug,or boot look bad,replace the spark plug,and if the boot is burned or distorted,replace it,a fuel injector can cause a miss fire also,but change the spark plug and see if this solves the problem,if not replace the coil,if it is a dead miss,then the coil might be bad,as for the water in the fuel ,the cap is missing,,and 5 dollars worth of HEET will not hurt,also,fuel from the fuel station,can have water in it.It happens a lot.

I had the same problem but eventually lost reverse. Had to get a new transmission... $2,300.00

i went to advance auto and they pulled the check engine light code and they said it was just wet electrical equipment from all the rain we have had and that it would dry out in a couple of drives so they reset the code and told me to come back in if it comes back on.

The main problem could be a well known cobalt ignition issue. check all fuses, wires, and connections if you've worked on cars before and call to see if you still have any warranty left. This should be handled by a chevy dealer or chevy trained mechanic...to isolate the issue fast and avoid repeat visits to get er done.