i have a 2.4 09 hhr service esc light and service traction light comes on and off,then my check engine light comes on,code reads misfire cyl 4,was told replace plugs..did replace them and still doing it.i know it could be coils injectors etc,has 75.000 miles on it.have extended warranty, but they seem to be baffled as to what to do .....any ideas, i was going to take the coil from cyl 2 and swith them thinking if it was the 4th coil it would show cycl 2 misfir if that coil was bad...any help would be greatfully appreicated....thanks don

 

What was the code? Always post the code itself as often the description is misquoted from the person downloading the code.

Swapping the coils is a good next step.

However, to a search using the SEARCH tool at the top of the page - search for the code itself, and you will find a multitude of causes, from plugs, coils, injectors, valve/head issues documented.

 

P0 304 is the code

 

" but they seem to be baffled as to what to do "

Who are "they"? You do not have to go to the shop that sold you the warranty.

I believe you also have a 5 yr/100,000 mile factory drive train warranty (engine & transmission). That requires a GM shop. It is their problem, not yours.

If the shop doesn't know how to diagnose an OBDII code, you need to find one that does.(that is a PERIOD)

 

Here's a thread that led to a problem with the valves after exhausting (pun not intended) all other possibilities: https://www.chevyhhr.net/forums/problems-service-repairs-42/p0304-code-witts-end-21238/

donbrew is right - it's the dealers problem - if they can't solve it, escalate it within GM or try another dealer if handy - your owners manual will have the phone numbers. just make sure you keep all workorders and document document document.

 

finally took it in,,, ,they ran a comp check on cylinder 4 found the cyclinder was messed up..so upon removal of the head,they found a burnt valve, tried to put in new exhaust valve ran a check and it wasnt sealing properly..so they replaced the timing chain,,tensioner,replaced all 16 valves, new head,cam shaft actuaters.no more misfire no more service esc light and no more service traction control.....happy camper all done under the 5 yr/100,000 mile warranty 09 model 2 lt 80,000 miles on the motor...thanks for all the help.....Merry Christmas..

 

And a brand new engine (basically)! Santa and the General work together.

A side note: This give credence to "you can't fix the head" they are just machined too close, you have to replace them and sell the scrap metal.

 

Hi Don,

I'm glad that the dealership was able to get this taken care of for you. Keep us posted if anything changes.

Happy New Year!

Jonathan A.
Chevrolet Customer Care

 

Good deal - glad it worked out for you. And a Merry Christmas right back at you and yours. :)