Question about Chevrolet Equinox

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Im trying to get my mother in laws 2006 chevy equinox to pass emissions the codes po171 and po420 keep coming up po171 is lean bank one and po420 is catalyst below efficency im trying to narrow it down to a part i can replace any suggestions are welcome

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For the lean condition I wound look for vacuum leaks.I you don`t find any then replace the o2 sensor for bank 1.As for the po420 if the exhaust system is not bent or damaged you will have to replace the catalytic converter.The catalytic converter has a longer warranty then the regular vehicle warranty itself so call the dealership and find out if the converter is still under warranty.The usual warranty I believe is around 80k.mileage years is 7 or 8 not positive.Hope this helps.Good luck.

Posted on Sep 15, 2010


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Chevy Cobalt 2006 2.2 liter engine

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with the first code it could be a faulty vent valve or solenoid
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I have 99 Chevy Malibu. My check engine light came on. The original codes were for a cylinder misfire and a small emissions leak. I replaced the injector for the cylinder that was misfiring as well as all...

well if you get it scanned again, and you get a lean bank 1 and 2 code then you may have a intake manifold gasket thats leaking. I just worked on a van that had them codes. and I ended up changing the intake manifold gaskets to get it to pass the emissions test for inspection, I live in new york state, po171 and p0174 are the lean codes. we did the maf sensor, new 02 sensors, egr valve and still got this lean code. good-day and god blessyou. it was on a 99 ford windstar van.

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I have a 1999 chevy silverado with 5.3 v8 po171 & 174 and po420 in that order at times the truck seems to loap when at idel any ideas where to start?

Thes code 171 nad 174 are bank 1 and bank 2 system to lean(02 sensors). these are probably causing the 420 catalist efficency below threshold. The first place to start is all the vacuum lines. check for vacuum leaks. when you get the first two codes 99% of the time it is a vacuum leak. 1% is the mass air flow meter/sensor. And I don't believe you have one on your truck. to old. Also you have to check for vacuum leaks around the intake manifold. use WD40 , spray around the manifold gasket areas if the engine runs better you found a leak.

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I have a 2006 Trailblazer. When it is cold outside the check engine light comes on. The code is P0171. But all summer and when temp is above 40 it goes out and stays out til the next cold day then comes...

Code P0171 is a lean oxygen sensor code for bank 1 on your engine. Bank 1 is always the side of the engine where #1 cylider is located.

There are a couple of Technical Service Bulletins (TSB's) that may apply to your problem.

Bulletin No.: 09-06-03-004C
This bulletin covers intermittent problems due to oxidation problems in some of the wiring connectors.

Bulletin No.: 03-06-04-030G
This bulletin outlines repair proceedures for clogged or restricted fuel injectors.

The only other thing I can think of would be a vacuum leak that occurs only in cold ambient temperatures and only affects bank 1. (possible intake manifold gasket or something similar.)

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Sounds like you have low fuel supply or a leak in intake system causing lean codes, check fuek pressure and volume first. Cat converter effeciancy could be caused by the lean codes, purge system sounds like solenoid failure, check for high resistance accross purge vent solenoid.

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A po171 code came on my scanner i need to know

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