I have a 2008 HHR. I take very good care of it and never had any problems until I reached 97,000 miles. The check engine light came on and it jerks when shifting into gears. It was diagnosed with code P0303. So far I had the spark plugs replaced and the coil package on #3 (the third one to the right looking at them from the front, RIGHT?) it runs better, but still jerks and the light is still on. Now the tire monitor light is also blinking on. I am very stressed out since it needs inspection and it doesn't pass. What do I do next?

 

No. #1 is at the front of the engine (passenger side) then in order 2,3,4.

 

Was the CEL reset once the plugs and coil pack was replaced (and the light went out)? If not, it needs to be reset to clear the error code. If it was reset, you need to double check the current code to see if it has changed.

A misfire as indicated by the p0303 code can be caused by a number of things including carbon buildup (which can sometimes be addressed by a good fuel cleaner - some swear by SeaFoam, or running a tank or two of a higher grade of gas) - or it can be caused by damage to the valves itself, which can get pricey to repair.

for your tire monitoring system, have you checked your tire pressures to see if they are within specs for air pressure?

 

Welcome to the site! Check these things and get back to us.

 

Thank you. A coil was replaced on #3.

 

Yes, it was reset, but it came back on with the same code. Seafoam was put in it 2 days ago. Light is still on. Should the light have been reset when it was put in?

 

Run the car for a few days it might clear itself. Or have your local parts palace clear the code for you, or dis connect the negative battery terminal for 30 minutes

 

Note the reference to disconnecting the NEGATIVE side of the battery to reset the light and code. Only disconnect the Negative side.

Do NOT disconnect the positive side of the battery, nor short the negative side to the positive side with a wrench. One can get seriously hurt that way.

 

Thanks! I will do that.

 

You'll need a 10 mm wrench, be careful as Whopper said