2000 Chevy Blazer engine codes

Tiny
GHAYES
  • MEMBER
  • 2000 CHEVROLET BLAZER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 190,000 MILES
My check engine light is on I had my computer checked for codes and it said that my mass air flow sensor, cam shaft sensor and intake manifold pressure sensors were all coding i've changed all of these to no avail. My blazer still idles rough for approximatley the first 20 seconds then the idle is fine. What else be setting these codes off is there a vacum line that would affect these i've visualy checked these and can't find any thing wrong with them also about this time my tach. Quit working.
Monday, June 15th, 2009 AT 3:38 AM

4 Replies

Tiny
RACEFAN966
  • MECHANIC
  • 5,029 POSTS
Ok can you get me the actual code numbers? Have you had the codes cleared sense you replaced the parts? Let me know what you can.
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Monday, June 15th, 2009 AT 1:47 PM
Tiny
GHAYES
  • MEMBER
  • 3 POSTS
Two of the codes are po340, po102, ihaven't had them reset I was told that they should clear after so many start ups and/or miles driven. I also noticed that my pcv valve makes a clicking noise that I can hear from inside my blazer I just noticed this today
my pcv valve is relativley new. I did'nt have codes cleared because the problems still present.

Thank you
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Monday, June 15th, 2009 AT 5:50 PM
Tiny
RACEFAN966
  • MECHANIC
  • 5,029 POSTS
Code P0340 is for the cam sensor and the P0102 is for the mass air flow unit. Now the codes will not go away on there own and the light usually will not go out. You need to have it cleared. The computer still sees the codes therefore it is still running with that. Meaning that the computer has preset information if a sensor goes bad and once replaced it still runs with that untill the codes are cleared telling it differently. So do that and lets see if any of the codes come back and go from there.
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Tuesday, June 16th, 2009 AT 10:23 AM
Tiny
SWILLIAMS
  • MECHANIC
  • 597 POSTS
With the tach failing at the same time the problems started I am almost sure it is NOT a sensor problem. It sounds more like the power or ground for them has failed. Check ALL the fuses first. Then check for the 5 volt signal at each of the sensors. Also check the ground side of the connector. I'm thinking you will find no voltage feed to the sensors and that is what is actually causing the codes. Bad ground return can do the same.
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Tuesday, June 16th, 2009 AT 12:42 PM

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