Check Engine Light On

Tiny
FLYGIRLBREE
  • MEMBER
  • 2007 CHEVROLET HHR
  • 70,300 MILES
Check Engine light on. Started months ago. It would come on and last for 2 days, then go off more a few weeks, then start to come on more and more often and would turn off for a few days. Now Engine light remains on and has been for four weeks. Will not go off.

When this light is on, it shifts hard, idles rough, eats gas like crazy.
Have tried 91 Oct. Gas even though it says 87 in the manual. Tried tightening the gas cap several time. This car has had its regular maint. It needs to be smogged now and I know it will not pass with the light on.

Help please anyone.
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Wednesday, May 29th, 2013 AT 8:26 PM

3 Replies

Tiny
CARADIODOC
  • EXPERT
The first thing is to have the diagnostic fault codes read. When the Check Engine light turns on in a Chrysler product there WILL be a fault code to indicate the problem. With GM products it is fairly common to not have a code so you don't know what caused the light to turn on. If you do get a code it's important to understand they never say parts are bad or to replace a certain part. They only indicate the circuit or system that needs further diagnosis.

The high fuel consumption is likely related to the fault code(s). The Engine Computer detected a problem is has been trying to tell you about it. Don't keep on ignoring it unless you don't mind buying more gas than necessary.

Higher octane gas is definitely not the solution. That higher octane means the fuel is harder to ignite. That allows engineers to design an engine to produce more power. The fuel does not produce more power on its own.
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Wednesday, May 29th, 2013 AT 10:13 PM
Tiny
FLYGIRLBREE
  • MEMBER
Thank you for the info. I tried the higher octane for three weeks. I am no longer using 91. I have been using 87 for several weeks. I have had it tested for a good which read misfire.
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Wednesday, May 29th, 2013 AT 10:19 PM
Tiny
CARADIODOC
  • EXPERT
Do you mean it had a misfire fault code? '96 and newer models will tell you which cylinder is misfiring by the number of the code. The cause can be as simple as bad spark plugs, and bad spark plug wires on engines that still use them. Less common causes are a bad ignition coil and a plugged or shorted injector. GM also has a lot of injector trouble. They can cause misfires that the Engine Computer will detect but you can't really feel.

Once you know which cylinder is setting the code you can switch parts between that and other cylinders, then see which cylinder sets the next misfire code. Instead, if it's been a long time since the spark plugs were replaced, it's just as easy to start with them. Replace the spark plugs, have the fault codes erased, then drive the car to see if a new code sets. Most cars since the mid '90s can get 100,000 miles on a set of spark plugs, but it is not unreasonable to find them causing a problem at the mileage you listed.
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Wednesday, May 29th, 2013 AT 11:18 PM

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