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Gm Tech (Cam)
Gm Tech (Cam), GMC Mechanic
Category: GMC
Satisfied Customers: 1686
Experience:  GM Grand Master Technician 2007. 14 year experience.
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GMC envoy 5.3 liter

Customer Question

have 2005 envoy 5.3 liter started having problems with oil pressure guage last winter with dtc code p0521. didn't have any problems this summer until it started to get down around 40 degrees started to have problems again. replaced oil pressure sensor still didn't help.also have intermitten starting problems       I asked this question yesterday and haven't received a reply yet. could somone please HELP !!!     
Submitted: 5 years ago.
Category: GMC
Expert:  JHoop replied 5 years ago.
Hello , my name is XXXXX XXXXX thank you for choosing Please tell me all of the problem as my answers are based on the information you provide. Your satisfaction is my goal, and I'm happy to answer any follow-up questions you may have about the same problem.

Sorry about the delay. Still need help?
Customer: replied 5 years ago.
now with the colder temp. when you first start up and start driving as it warms up the pressure gauge goes down to zero. if you shut it off the pressure gauge goes back up and slowly goes down to zero with warning no pressure shut off stated i replaced the pressure sender and it was worse,so i put the original back in.
Expert:  JHoop replied 5 years ago.
Any engine noise? All is well with that engine?
Customer: replied 5 years ago.
yes, this problem has been going on since last winter when it was soon as it got above 40 degrees we didn't have problems all summer.when the warning comes on to shut down engine,there isn't any engine noise as far as lifter or low oil pressure noise from lower engine
Expert:  JHoop replied 5 years ago.
Is that connector to the oil pressure switch been verified good? The wiring to it?
Customer: replied 5 years ago.

no,but i would not expect the pressure gauge to react to restarting vehicle, and difference between the the new and existing pressure sensor. the existing sensor shows higher pressure and reacts better to restaring engine.


Expert:  JHoop replied 5 years ago.
I'm going to put your question back up and see if anybody else has any info on this. Sorry I couldn't help you further. I'm sure someone will be with you shortly. Please do not reply as it will lock me to your question and no other expert can answer you. Thanks again for choosing justanswer! JHoop
Expert:  FIX IT MAN replied 5 years ago.
Hello jacustomer, does this happen every time you start the vehicle when cold? Does it ever happen when warm? Is the check engine light still on? Will it change as soon as the vehicle is restarted?