2005 Chevrolet Cobalt SES comes on.
Have codes = p0171 lean.
Why does my check engine light come on. I took my Chevrolet  cobalt to auto zone to have them
scan the computer because the
check  engine light was on. They said the OBD2 pcm code was
p0171 lean. What does this mean. Do i need an oxygen sensor or is there another problem. Why
does my check engine light come on. Thanks.
There are a few reasons for the code p0171 lean condition on this car and engine. It is possible
that the
oxygen sensor is bad, but m ore common is that the air intake cover is loose and leaking
vacuum to the throttle body assembly. This is the large black plastic engine cover on the center
of the engine. If the air filter has been checked recently, or had an oil change done where
someone checked the air filter, then they may not have gotten the cover on the throttle body
correctly, causing a lean condition and code.
Another common thing to correct this is that there is a PCM
(powertrain control Module) software programming update to correct a false p0171. This would
need to be reprogrammed with a dealer scan tool. These condition also apply to the chevy HHR,
Malibu, Pontiac pursuit, and Saturn Ion.

2007 Chevy Cobalt.
Replaced temperature sending unit for engine and new control head on dash for heating and
A/C. When engine temp does not read out on multifunction read out on dash ac compressor will
not turn on .What could cause this?

If you've got a bad thermostat, such as stuck open and the engine can't reach operating
temperature, or stuck closed and the engine runs hot, the air conditioning system will default to
off until the problem is fixed. I'd recommend doing a scan of the car's computer. Even with no
check engine light on, you may have set a code for a temperature problem.

Usually when this happens the temperature gauge, or display in your case, will not function and
the car's fans will run constantly. If you're experiencing this as well, then you know the thermostat
is to blame. If that doesn't seem to be the case, I'd still recommend getting a scan done where
you can actually see if the air conditioning is being commanded on or not from the car's
computer. That might help lead in a direction of proper diagnosis.
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2005 Chevy Cobalt P0171 Lean