I have had lots of problems with my ESC light on my HHR. Hearing other's solutions I've replaced both front Hubs, replaced the intake and exhaust solenoid valves, cleaned all fuses, and still getting same error code messages as listed below from Auto Enginuity Scan Tool:
12/12/2013 06:42:35
Chevrolet HHR 2009
Generic Powertrain
P0302 Cylinder 2 Misfire Detected
Freeze Frame for DTC P0302
Fuel System Status Bank One Closed Loop
Fuel System Status Bank Two Not Reported
Calculated Load 56 %
Coolant Temperature 192 F
Short Term Fuel Trim Bank One -10.14 %
Long Term Fuel Trim Bank One -3.12 %
Intake Manifold Absolute Pressure 19.8 in.hg
Engine RPM 1969 r/min
Vehicle Speed 14 MPH
Ignition Timing Advance for #1 31.0 deg
Intake Air Temperature 37 F
Air Flow Rate From Mass Air Flow Sensor 2.75 lb/min
Absolute Throttle Position 35 %
Absolute Throttle Position E 18 %
Commanded Throttle Actuator Control 32 %
Alcohol Fuel Percentage 9 %

Thanks in advance to ANY help you can offer! And by the way, hope all of you have a GREAT New Year!!!!

 

Long term fuel trim seems to be your key. It should be very close to 0 and Short term should not be that far negative. My guess is #2 injector is bad, Might also be one of the O2 sensors.

Try switching the #2 injector around, clear the code and see if it changes cylinders.

Congratulations on giving us something to work with, but year,model, engine would also help some.

I'm going to make a new thread out of this.

 

Thanks for moving this Don, just as I finished reading his data, our DSL dropped out.

I concur that the #2 injector is suspect, especially in light of the long term fuel trim.

Checking the OP's profile tells us that it's an '09 model year, but engine size etc., would a great help. And bravo for providing so much info, if only everyone had a Scan Tool.

 

I've already tried switching injectors to move error code with no change. It's a 2009 LT2 with the 2.4 engine. I've switched the #2 coil & spark plugs in an attempt to move the error, with no change. It amazes me how many people have had a problem at high speeds, while I seem to only have the ESC light come on while either driving slow or at an idle, and even a few times when I first started the vehicle before putting in gear. When the ESC light is on I feel rough shifting and poor engine performance.

 

You are now getting into the REAL expensive area. Compression and leak down tests are called for now. You did clear the code after doing the switching, I assUme.

Are there any pending codes? I'm hoping to find something that points to a EVAP problem, or even an O2 sensor. Not all codes will light the CEL on the first occurrence, in fact most of them take 2 consecutive "cold start" cycles. The P0302 takes multiples I'm surprised you don't have P0300 also.

The ESC will put the car into "limp" mode. In the mean time check your brake fluid level and your brake pads for wear and the rear brakes for adjustment. Those can cause ESC.

 

A few years back we had a member with a similar low speed ESC issue that ultimately traced back to a wheel speed sensor that had gone intermittent.

But in that case there was no error code for a misfire stored, and being that you've already moved things around without the misfire "following" them, obviously more digging is required.

The plug that came out of cylinder #2, do you recall if it was fouled or "steam cleaned" in appearance. Also, what plugs are you running?

Rough shifting and poor engine performance do go hand in hand with an ESC error.

How many miles are currently on the vehicle, and have you noticed any loss of coolant over time, or milky deposits on the dipstick or underside of the oil fill cap?

And I see Don is suspecting the same thing that I am, and he beat me to the punch with a compression and cylinder leak down test.

 

I am able to read and clear the codes at any time, and have recorded several of the freeze frame data records. In them I see the Long Term Fuel Trim is reading between 3.12 to -5.45 . I hace a Excel file compiling this data, but a lot for this foram. There is currently 125,000 miles, and I have been fighting this problum for about 25,000 of them. As I do my own Oil Changes, I have watched the coolant level, and moisture in the crankcase. The car had front end damage causing a replasement of the radiator and coolent at about 85,000 miles.

 

Basically, what we're suspecting is a head gasket failure, or the worst case scenario, a cracked head.

I'd recommend, especially since you're mechanically savy, doing a compression check across the board and a cylinder leakdown test.

A healthy Ecotec should have between 155-180psi in each cylinder on a compression test, GM specs state that there should not be more than a 70% variation between the highest and lowest cylinder.

 

I would consecrate on you misfire code first. As recommended compression test. The long term trim will be affected to the negative from a misfiring cylinder.

As a side note: has your reading in the past for alcohol % always been around 9 ?

 

I found another thread on this forum, where a HHR needed a new head and valves because of a scan code of P0304 with a misfire on NO 4. This follows what I hear on this thread. I will do a compression test and hope for the best. I appreciate all of the advise given and knowing the specs. to look for. Thanks!!! As for the alchohol %, it is running from 3 to 14 %, depending on where gas is purchased.