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t-codes 171 and 174


reyes45's Avatar
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Join Date: Mar 2003
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04-21-04, 05:48 PM   #1  
t-codes 171 and 174

On my 98 sierra, 4.3lt. my check engine went onand it registered codes 171, and 174. What could have coused these codes. Thank you.

 
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smogtek's Avatar
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Join Date: Feb 2004
Posts: 248

04-21-04, 07:17 PM   #2  
Both front O2 sensors are seeing a lean condition.

Possible causes:

Lean fuel condition caused by low fuel pressure, restricted fuel filter, clogged fuel injector(s), etc.

Vacuum leak in a hose or intake manifold gasket leak causing the O2 sensor to see a lean condition.

Those are some of the most common reasons.

Check (or get checked) the O2 sensors to make sure they are responding to fuel changes. Easy job for a technician that knows what he's doing.

Matt

 
reyes45's Avatar
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04-22-04, 05:27 PM   #3  
thanx matt,
I found that the pcv hose was leaking. I replaced it and erased the codes and they haven`t poped up yet. thanks for your advice.

reyes45

 
smogtek's Avatar
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04-22-04, 09:15 PM   #4  
Sounds like you got a good fix on it. Congrats.

 
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