2003 GMC Sonoma truck running bad

130,000 MILES • 4.3L • 6 CYL • 4WD • AUTOMATIC
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JASON520SEXTON
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  • 1 POST
Code told me to change mas air flow sencer and map sencer and I did and still runing bad and sending same codes still
Feb 22, 2014 at 6:41 AM
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CARADIODOC
  • ✓Experienced Mechanic
  • 34,400 POSTS
Diagnostic fault codes never say to replace parts or that they're bad. They only indicate the circuit or system that needs further diagnosis, or the unacceptable operating condition. When a part is referenced in a code, it is only the cause of that code about half of the time. You first have to check the wiring to that part. This is especially true when you have two or more related codes. Look for what they have in common, like 5.0 volt feed and ground wires. The place to start is with a scanner that lets you view live data. The MAP sensor voltage must be between 0.5 and 4.5 volts. That's the easiest circuit to diagnose.

It's also necessary to know the exact fault code numbers. There can be over a dozen related to one sensor, and they mean very different things.
Feb 22, 2014 at 8:37 AM
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