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Eng fault codes P0171, P0174 Bank 1&2 Lean

 
corvet02
I love my Chevy Chevette!
Posts: 1
Joined: 02/09
Posted: 02/15/09 11:23 AM

Ive got 2002 ZO6 with fault codes P0171 and P0174- book says bank 1 and 2 are lean. Dealer said with the after market cold air intake (Halitech) and stock MAF will usaully be the cause of these faults. The dealer cleaned and cleared the codes. Within 5 miles of leaving the dealer the eng lite was back on and the same 2 codes are present again. I found the MAF was not cleaned as they said but I replaced the MAF with the after market MAF from Mid America for these types of cold air intakes that I currently have. The codes were reset once again and have since within a few miles have returned. Any help would be great on this....  

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denniner
I love my Chevy Chevette!
Posts: 2
Joined: 03/10
Posted: 03/15/10 09:41 PM

You may want to check for low fuel pressure or a vacuum leak in the intake tract.  Laugh  

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STech
I love my Chevy Chevette!
Posts: 1
Joined: 12/10
Posted: 12/21/10 08:08 AM

Icon Quotedenniner:
You may want to check for low fuel pressure or a vacuum leak in the intake tract.  Laugh

I have the same codes on a stock 2003 50th Anniversary with 88,000 miles. Do you think that the oxygen sensors could be bad - the ones before the catalytic converter if they have never been changed? Would you know where they are located in order to change them? Thank you!  

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waynep7122
I mow my lawn and find Chevys
Posts: 1114
Joined: 08/09
Posted: 12/21/10 05:24 PM

i would think that i would also change the fuel filter first..   see how clogged it was....

check the fuel pressure to make sure the fuel  pumps are not damaged.. and are putting out the proper volume...

FILTER ASM,FUEL
Ac Delco Part Number:  GF822
Product Notes:
[Fuel Filter]; Except 2nd design fuel system (FFS)
Per Vehicle: 1; Years: 2003-2003

http://images.whisystems.com/smartpages/partinfo_resize/DUS/GF822.jpg


vacuum leaks... could cause it also...   got any loose hoses.. or vacuum  hoses that have collapsed...

the chance of both oxygen sensors both setting codes... do to the sensors being bad... slim...

with a scan tool... you can look at the live data stream... check the sensors voltages...   many scan tools can graph the oxygen sensor voltages... watching to see if the sensors are bad.. or not...

would you like to read up on it... i can link some articles on oxygen sensor testing...

there are several other things that could also be wrong.. but thats where i would start...  

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waynep7122
I mow my lawn and find Chevys
Posts: 1114
Joined: 08/09
Posted: 12/21/10 05:28 PM

http://www.obd-codes.com/p0171

http://www.obd-codes.com/p0174


looks also like you might want to see what the mass air flow sensor data stream is....   with a scan tool...  

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