I have a 2009 Chevy Aveo LS, 4 door sedan with 5 speed manual transmission and 1.6 Ecotec egine. About one week ago I got the infamous flashing yellow engine symbol light and car began to run rough, idle rough, lose lots of power and gas mileage drop 10 mg a gallon immediately.

1) Went to Autozone after checking on this website and researching the internet for others that may have similar problem. Code reader at Autozone gave a P0303 cylinder misfire #3. Thus I bought 4 new spark plugs, Platinum NGK V power to replace the copper tipped NGK from factory. Hoping this might be solution or at least a cheap fix if lucky. After finally figuring out how to take off the black plastic cover to the engine ignition coil pack that had the four spark plugs under it, I changed out the old plugs and put in the new ones.

2) NO LUCK, car did run noticeably better but still flashing yellow engine light and slight rough idle within few miles of driving with new spark plugs. So call dealer and set up appointment to have them run their diagnostic machine check on the Aveo. This will cost you so expect to plunk down at least $75-$100 just for them to hook the machine up to your car but it is worth it.

3) Today I am $307 poorer! Yes, I have over 57250 miles on the car, all highway, so warranty of bumper to bumper was expired and no good. Apparently after doing more research, Aveos seem to all have a problem with their ignition coil or what the dealer calls coil or coil pack or coil bridge which sits on top of the four spark plugs with 4 black rubber boots that look like tits on a cow hanging down, literally. Inside those black rubber boots are the spark plug wires. Basically unlike other cars where you can just change out a bad spark plug wire for $25 or less and take out bad spark plug wire and put in good one, Chevy Aveo does not allow for that, YOU will have to buy the entire new coil pack or ignition coil pack, there is no way to fix just one or replace that bad spark plug wire, thus you have to buy the entire coil!

3) After doing much research and seeing other Aveo owners comment and checking ODB code reports, around 30,000 to 60,000 miles on Aveo there is a high probability that you may have a spark plug wire go bad inside this coil pack causing your check engine light to come on or stay on or flash or blink and it may give you the P0303 code. Thought others on here would like to know this so they do not drive themselves crazy trying to figure it out or spend lot of money on other areas trying to fix this problem that are not necessary.

4) I paid $144 for the labor and diagnostic machine reading plus $152 for new coil pack today. I got off easy I thought considering that I priced a new coil pack at Autozone and Oreillys last week and both were $762 - $815 each! I only found one other place online that had the new one for $426 for the coil pack alone. Granted it is not hard and is easy to install this coil pack, simply disconnect the connection plug on side of it, unscrew 2 Torx size 40 screws, lift up coil pack then put the new coil pack in it's place and done, then re-connect connection plug and put back in screws. Only should take 5-10 minutes at most. Key here is finding that coil pack though under $300, just was not able to do it so I took it to the dealer.

5) WARNING For those of you that think, oh what the hell, I can drive it anyway, so what if I lose a little power and light flashes or it idles rough I will get it worked on later when I get time. DO NOT DO THIS. You will ruin many more other parts or components that tie into your emission system, engine system and exhaust system which will screw up the catalytic converter, O2 sensor, and many other miscellaneous parts. The first two mentioned will run $150 for O2 sensor or more and the catalytic converter will run around $1000 or more to fix plus it could even harm engine valves and heads, not counting the labor also.

So it is not worth it. Go get it fixed immediately or stop driving your Aveo until you can have it fixed.

Had mechanic today tell me that he had worked on 3 other Aveos last year that the owners had ignored this warning light and kept on driving the car for many more thousands of miles until it would not hardly run or start at all, then try to have it fixed and ended up causing serious damage to the Aveo and having a several thousand dollar repair bill. Thus if you get one of these flashing engine yellow lights or the light stays on constantly or you go to Autozone and get a code reading of P0303, I strongly recommend you go to your dealer ASAP and or if you know where to find one of those new coil packs for less than $152 you can do it yourself.