i recently have started the chasing of engine codes, I have a 2009 Chevy HHR LS 2.2 with 73,000 miles. the first time my engine came on the garage told me the code po171 ( fuel trim system Lean) ok and the fix was O2 censor and replace spark plugs and #3 cylinder coil replacement. ok done everything good right!!!. well wrong Engine light came back on with another code of PO303. and that is cylinder #3 misfire and still the code of PO171. Everything has been fixed and codes erased but with in a few miles of driving the engine light comes back on with same codes pO171 and PO303, next is fuel injection system going to have a new engine by the time I'm done chasing codes

 

I moved this to a new thread.

Typically P0171 means a vacuum leak. Too much AIR, not Too little Fuel. Hardly ever O2 sensor.

P0303 does mean a cylinder 3 misfire. However diagnosing is required. First test is switch #3 coil and #2 coil, then #3 plug with #2 plug. If the code changes to P0302 either time then you have found the specific problem.

Next test is Compression and leak down.

Have you noticed coolant disappearing, or oil level increasing or oil burning?

I would look for a shop that actually knows what it is doing, the one that threw parts at it is a rip off.

 

Good points Donbrew - to help save time if one is paying for a mechanic, to narrow down the problem one can swap coils between cyl 3 and 2, plugs between 3 and 4, and fuel injector between 3 and 1, all at the same time.

Throwing new parts at it these days for the complications in "todays engines" can get very expensive - one is more likely better off to swap the easy stuff first to see if the problem moves.

 

Hi, welcome to the site, for the P0171 code have a look at the vacuum hose from the elbow of the intake tube to the throttle body to the valve cover

Here's a link,


http://www.obd-codes.com/p0171

 

FYI ccwrathchild - make note the error codes are NOT po171 and po303 - they are p0171 and p0303 (the last 4 are numeric). So if you are doing a search/google for po171 you aren't likely to find much at all.

 

I Hear Ya Im Crazed With Chasing the light