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So My mom and I have a 2008 chevy equinox. We can not pass our emissions test. We have changed gas caps three times.
P0455,P0133, P0442, P0451, P0454, PO455,P1133, P0464, AND P2A01..
I have little to no experience with cars although I have been studying the codes and evap system.
Any ideas?
Im thinking replace pressure sensor, and oxygen sensor??
 

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2010 chevy equinox 2.4
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Just replace the upstream 02 sensor and the battery or just the battery first. The majority of those codes are fuel/ evap related. The car uses the battery for like all of those codes. Evap codes are usually set when the car is off running diagnostic tests under battery power. If you're under like 12.4v car off it will throw those codes. Considering the year you should definitely replace the upstream 02 sensor. One code can cause multiple codes all those p04.... Codes could be the battery or a huge fuel vapor leak is also common. If you have a scanner with i/m readiness you could literally disconnect the battery, do a full drive cycle to register all the smog equipment (1 hour drive) and smog literally the same day. Once you shut the car off and it does a self evap test under certain temperature conditions the computer might pick up a code... Those evap codes may go away but when 02 sensor codes are set they are perminant and will not turn off without the car bieng fixed and the computer triple checks it. Just also take a peak underneath and make sure there is no obvious damage around the gas tank. A really common problem is also the evap purge valve gets old that could be your problem. Either way with code after code like that I would see that as a complete system failure and REALLY you have about 10 other codes to look at in the p04... Category.... The car guesses as close as possible often times its a code or 2 off like that p0455 could be the main cause for all those p04... Codes ( large leak in tank) that pops up when engine is off though. First... Try disconnecting the battery for 15 plus minuites. Then after re connecting there should be 1 or 2 codes that come up that is where you should check first. Since the evap monitor is the last system usually to register in the cars computer some / most shops will push it through smog with no register on the evap, as long as everything else is ready they usually let/ are able to pass inspection as long as no codes are set. They have a algorithm they use like fuel leaks yes no, smoking yes no they type in manually.... The evap is a yes/ no question.
 

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Some states will give you a pass on EVAP readiness if all the other monitors are good.
Except NJ, been there. Even CA will give you a pass.
 
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