I have a '00 Buick Century Limited and the service engine light has
been coming on. I checked it with an ODB-II and it read P0172. Now, I
have changed the Oxygen Sensor, however it is still giving the same
error. I ran a bottle of Injector Cleaner through and the light still
came back on.
I haven't checked the MAF with a voltmeter yet, but I will and I doubt
that this is is. What else could it be? A bad injector? I'm running out
of ideas so any help is greatly appreciated.
Why would the first thing you do is replace the oxygen sensor for a P0172?
Start with the cheap stuff: change your air filter and clean your throttle
body. Look for a blockage in the intake. Check the vacuum line going to the
fuel pressure regulator for fuel, if there is fuel in the line, replace fuel
pressure regulator. Check fuel pressure. Run injector cleaner through the
system (which I see you have done).
If you have a scan tool (not a code reader), check for proper operation of
the MAF, IAC motor and TP sensor. At this point, I would take it to a good
mechanic and let them do a quick diagnosis, they should be able to find the
problem quite quickly. Then you can take it and replace the offending
Well, I thought that the O2 sensor might have been bad and it was one
of the listed possible causes. No big deal. One other clue that may
narrow it down is that the Service Engine light only comes on when the
gas tank gets lower... on a full tank the light doesn't come on. Does
this help at all?
I don't have a scan tool unfortunately, the best I can do is to use a
voltmeter on the MAF harness to check for 12v.
Oxygen sensor IS one of the possible causes, but it's down on the list. Did
you check the other things I mentioned? If so, I would seriously consider
taking it to a mechanic, he'll tell you what's wrong. Most likely something
any competent mechanic can diagnose in well under an hour.
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