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Discussion Starter #1
code reader says P 0451 evap system pressure switch, a circuit
any one had this work done , was it expensive to fix?
 

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2014 ATS 3.6 Premium RWD, 2016 Corvette Z06, 2018 GMC Sierra Denali 2500HD Diesel
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Jack,
My 2014 ATS had a series of issues with this in its first 500 miles nearly leading it to be a buyback. The underlying problem was a cracked storage canister and the dealer kept replacing different parts before finally replacing the canister and all lines.

Evaporative emissions systems are pretty simple but access to some parts of it is a pain. I would take this to an independent garage instead of a Cadillac dealer which will be much cheaper. A P0451 can be set because of a faulty sensor, solenoid, cracked canister, or damage to the vacuum line that pulls a vacuum on the canister. So if you decide to repair this yourself, start with a careful inspection of the hoses and canister (pull the purge hose and check for charcoal debris if a cracked canister is suspected) after check the canister outer shell.

California and some other states require a longer warranty on the emissions system than most of the country so check the warranty info for your state. I doubt that it is still in warranty (standard federal emissions warranty is gone) but this is part of the emissions system so specific states may have a long enough required warranty. This issue won't cause any issues with drivability so it should be addressed but it doesn't have to be done by tomorrow.
 

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Discussion Starter #3
Thank you so much rsingl for your comprensive reply. I see how this could turn into a money pit.
I now plan to do a check as best I can on my own and then take it to my local auto shop.
I understand theres no need to rush around, I have 5 months before a smog check is due.
 

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2013 ATS 2.0T AWD
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346 Posts
Jack,
My 2014 ATS had a series of issues with this in its first 500 miles nearly leading it to be a buyback. The underlying problem was a cracked storage canister and the dealer kept replacing different parts before finally replacing the canister and all lines.

Evaporative emissions systems are pretty simple but access to some parts of it is a pain. I would take this to an independent garage instead of a Cadillac dealer which will be much cheaper. A P0451 can be set because of a faulty sensor, solenoid, cracked canister, or damage to the vacuum line that pulls a vacuum on the canister. So if you decide to repair this yourself, start with a careful inspection of the hoses and canister (pull the purge hose and check for charcoal debris if a cracked canister is suspected) after check the canister outer shell.

California and some other states require a longer warranty on the emissions system than most of the country so check the warranty info for your state. I doubt that it is still in warranty (standard federal emissions warranty is gone) but this is part of the emissions system so specific states may have a long enough required warranty. This issue won't cause any issues with drivability so it should be addressed but it doesn't have to be done by tomorrow.

I wonder how much money/time is wasted by stealerships trying to rectify problems by performing useless repairs. I was once told in confidence (not anymore!) from a former dealer tech that as long as a car is under warranty, the dealer can charge the manufacturer for all the bogus 'fixes' before the actual problem is rectified. We all pay in the long run with higher sticker prices.
 
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