P0302 , My check engine light keeps going on and off with this code. I have failed inspection twice because the light was off and then popped on again in the bay while idling. It always comes on when the Chevy Trailblazer is sitting still. Can anyone help me with what I can do? Had engine repair two yrs ago, 2600. dollars worth of work on the second cylinder and now it is the same cylinder missfiring. Thanks ahead of time for your advice.

You can go to most auto parts stores AutoZone advance Auto Napa and they will read the codes but before you do that disconnect the battery cables and clear the codes that are already set so the check engine light shuts off then drive around 15 miles or so to give the computer enough time to set new codes when the check engine light comes on after the 15 miles now go for the code scan and any codes will be new and it's easier to find your problem and no old codes will be present which might've been fixed already but the keep alive memory is still storing the old codes also you will never pass inspection with the check engine light on and don't think you can pass inspection with the light off after clearing the codes there are monitors for the ecm that have to do there self check before the system is inspection ready and if they are not ready you will fail the inspection and still have to pay it can take as much as 80 miles driving or more and the gas tank should be between 1/4 & 3/4 full for the evap monitor to clear the self test in some cases it will take a few days for that monitor to clear the self test and the car will be ready for inspection the evap test is the last monitor to clear the self test and until it does you will not pass inspection you can look up the drive cycle info for the sequence to follow after all repairs are completed and a code 1000 is present telling the inspection computer that your car is system ready otherwise you will keep paying the fees and failing the test good luck this is the right info here I'm a taxi mechanic in NYC with 50+years of experience and you can count on what you are reading as the most important information you can get about this for you and anybody else who reads this thread this is 1 million percent correct and authentic good luck again Stephen

Fuel injector may be restricted or hung open .

The P0302 code means that the cylinder 2 is misfiring or is randomly misfiring. Start by checking for intake leaks and if no leaks are found the next step is to replace the spark plugs on cylinder 2. If the problem persist more tests needs to be done. PO307 is the same thing except number 7 cylinder. Possible symptoms - Engine Light ON (or Service Engine Soon Warning Light)
- Lack/loss of power
- Hard start
- Engine hesitation

It all depends on why your light is on. Most National part store chains offer free scanning to tell you what codes are stored and setting your light on. Sometimes clearing the codes will keep the light off long enough to pass the inspection, but either way you will know where the problem lies and will be able to get it fixed so you will not have to worry about it.

Nothing to your car, just the environment.

Go to this site: http://www.engine-light-help.com/generic-check-engine-light-codes.html

Your 'generic' codes are there for OBD-II

Misfire could be a number of things:
a) spark plugs - change them if used over 15K miles - inspect/regap.
b) spark plug wires - change them if over 15K miles - inspect
c) ECM (electronic control module) - test with HEI (high energy ignition) tester.

The shaking tells me that the engine is running on less than its normal compliment of cylinders - the shaking is produced by the imbalance caused in the engine by one (or more) cylinder(s)
not firing at all.

The "Check Engine" light probably is coming on due the the misfire condition. Go to Pep Boys or
Advance Auto Pats, where they'll tell you (free) your codes causing the "Check Engine' light to be
lit - the code coming from your truck's computer will probably be one or more of:
P0300 - Random/Multiple Cylinder misfire detected
P0301 - Cylinder 1 misfire detected
P0302 - Cylinder 2 misfire detected
P0303 - Cylinder 3 misfire detected
P0304 - Cylinder 4 misfire detected
P0305 - Cylinder 5 misfire detected
P0306 - Cylinder 6 misfire detected
P0307 - Cylinder 7 misfire detected
P0308 - Cylinder 8 misfire detected
P0313 - Misfire detected with low fuel

P0302-cylinder #2 misfire detected
P0420- catalyst efficiency below threshold bank 1
P0340-No cam signal at PCM.
The Cam sensor most likely needs to be replaced first. Clear the codes after that and drive and see what comes back on.

P0302 is a mechanical fault code meaning there could be a problem with the wiring or ignition/fuel system, could be a bad injector or ECT/MAF sensor or the ECM. (ECT=engine coolant temperature sensor)(MAF=Air flow sensor)(ECM=Engine control Module)

I would check and make sure your throttle position sensor is working correctly also check your egr valve.