How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Gary Your Own Question
Gary
Gary, GMC Technician
Category: GM
Satisfied Customers: 15692
Experience:  15 years gm master tech/15 years ASE master tech
19513769
Type Your GM Question Here...
Gary is online now
A new question is answered every 9 seconds

Check engine light came on and the oil pressure gauge

Customer Question

Check engine light came on and the oil pressure gauge dropped below 20. Then the turn off engine came on. I pulled over checked the oil and added 3/4 of a quart. This helped for a 20 minutes. Then when the vehicle is at an idle the oil gauge pressure drops and the turn of engine comes on again. I looked under the vehicle and around the motor there are no oil leaks.
JA: Does the light stay on, or does it blink?
Customer: The light only comes on at an idle when the oil pressure gauge drops below 20
JA: What is the model/year of your GM?
Customer: 2002 GMC Envoy SLT
JA: Are you fixing your Envoy yourself? What have you tried so far?
Customer: I have not done anything other than ad oil. Currently parked in the driveway.
JA: Anything else you want the mechanic to know before I connect you?
Customer: no
Submitted: 1 month ago.
Category: GM
Expert:  Gary replied 1 month ago.

Welcome! My name is ***** ***** I will do my best to assist you with this problem.

Expert:  Gary replied 1 month ago.

at idle when its reading low and the message is lit up in the dash is there any ticking or abnormal noises form the engine at all ?

Customer: replied 1 month ago.
No, there are no noises just the drop in pressure
Expert:  Gary replied 1 month ago.

this issue will come down to as simple as a bad oil pressure switch OR a build up of sludge in the bottom of the oil pan causing the oil pick up tube to not be able to pick up oil that good or a bad oil pump

with no noises i would replace the oil pressure sensor as seen in this picture right above the oil filter and give it a fresh oil change

if it still does this then the oil pan would need to come out to check the oil pick up screen and oil pump

dont forget to rate us here

you can always get me back for FREE for any follow up any time with this question even after you rate me here at Justanswer

if you have any questions please ask as i do not get credit for my work until you rate me here at Justanswer

Customer: replied 1 month ago.
The vehicle has 170,000 miles but I change the oil regularly as well as service it. I will get the gauge checked and have them drop the pan.
Expert:  Gary replied 1 month ago.

if they connect a mechanical oil gauge to the oil pressure sender port on the engine and confirm the oil pressure is good then the oil sender is just bad usually

if they confirm the pressure below spec then the oil pan needs to come off next

dont forget to rate us here

you can always get me back for FREE for any follow up any time with this question even after you rate me here at Justanswer

if you have any questions please ask as i do not get credit for my work until you rate me here at Justanswer