2007 Chevrolet Impala check engine light says on

Tiny
STCHRIS96
  • MEMBER
  • 2007 CHEVROLET IMPALA
  • 3.5L
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 137,000 MILES
Took the car to advance auto to have the scanner check scanner reading 02 oxygen sensor say engine is running rich on one side what should I replace on the car is it the mass airflow sensor or is it a bad 02 sensor car seem to running just fine to me
Sunday, October 19th, 2014 AT 9:34 AM

12 Replies

Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Did you get a code #? There are several 02 sensor codes, 02 performance codes, 02 circuit codes? If the 02 sensor is showing rich, could be, vacuum leak-- 02 sensor or sensor circuit problem, fuel injector problem, something like that.
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Sunday, October 19th, 2014 AT 10:25 AM
Tiny
STCHRIS96
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  • 28 POSTS
The code was 171
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Sunday, October 19th, 2014 AT 10:40 AM
Tiny
JDL
  • MECHANIC
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That is lean fuel trim code. You could try cleaning the maf sensor, see if it will help. The air filter clean? Check fuel pressure. You might have a clogged fuel injector?

There is a long list of possibilities, could be a vacuum leak, somewhere?
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Sunday, October 19th, 2014 AT 11:19 AM
Tiny
STCHRIS96
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  • 28 POSTS
Sorry the code was 172 rich reading could this also mean serious engine problems
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Sunday, October 19th, 2014 AT 12:25 PM
Tiny
JDL
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I'd use a gage and check proper fuel pressure. If you don't have a fuel pressure gage, some of the national brand auto stores will loan out a fuel pressure gage. You may have to put up a deposit, but, you get it back when you return the tool.

Not only check correct fuel pressure, see if pressure holds for a bit with everything off.
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Sunday, October 19th, 2014 AT 12:58 PM
Tiny
STCHRIS96
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  • 28 POSTS
Ok will do thanks what should the pressure be is it possible that the pressure is to high if is what should I do to correct it
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Sunday, October 19th, 2014 AT 1:02 PM
Tiny
JDL
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If pressure is too high, replace fuel pump module. My info says you have a returnless fuel system, pressure regulator and filter are at the fuel pump module. Fuel pressure is 56--62psi.
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Sunday, October 19th, 2014 AT 1:50 PM
Tiny
STCHRIS96
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  • 28 POSTS
Ok thanks one last question if the pressure is correct what should I do next
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Sunday, October 19th, 2014 AT 2:05 PM
Tiny
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I'd have to see what 02 sensor is doing.
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Sunday, October 19th, 2014 AT 2:21 PM
Tiny
STCHRIS96
  • MEMBER
  • 28 POSTS
Ok
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Sunday, October 19th, 2014 AT 2:25 PM
Tiny
JDL
  • MECHANIC
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Just go one step at a time, I certainly don't know everything, far from it.
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Sunday, October 19th, 2014 AT 3:45 PM
Tiny
JDL
  • MECHANIC
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Just to add, don't worry about all the possibilities, just take a basic step, checking fuel pressure, plus, see if it will hold for a bit with everything off. Go from there.
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Monday, October 20th, 2014 AT 9:52 AM

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