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goodwrench9124, ASE Certified Technician
Category: Chevy
Satisfied Customers: 3432
Experience:  Ase Master Certified, GM Master Certified Tech. Awarded GM Top performer, Hybrid certified
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2003 GMC Envoy: 800 miles..Fuel gauge..Needle..calibrated

Resolved Question:

2003 GMC Envoy, 50,800 miles. Fuel gauge suddenly stopped reading correctly. Needle moves at start-up but does not move to calibrated portion of the gauge. At start-up, low fuel warning light is "on" briefly than "off" as iusual. Voltage guage is reading 16.5 volts which is higher than I have ever seen before. Usually, this guage reads 14 volts. Over the last 24 months the service engine now light has been on almost continuously. The local dealership has inspected everything, tested fuel system for air leaks with no success. Vehicle runs normally. No apparent change in performance, gas mileage, cold weather starting ability etc. Please comment on appropriate diagnosis and lasting repair for these issues.
Submitted: 7 years ago.
Category: Chevy
Expert:  goodwrench9124 replied 7 years ago.
Hello, and welcome to JA!!! with the service engine soon light on, there should be a trouble code in the system. did your dealer scan the system for codes?
Customer: replied 7 years ago.
Yes, the dealer did scan for codes. Apparently, the only meaningful code pointed toward a potential "leak " in the fuel handling system. Atest was performed. I think they referred to it as a "smoke" test. Results were negative. The system was reset and the SES light disappereared for a while, reappearing after 4-5 weeks. I believe this light has been reset 3 times over the last 18-24 months. Nothing has been found. This issue continues as stated in the original question. It does not appear to have any affect on my vehicle. The fuel gauge and voltage gauge issue developed today.
Expert:  goodwrench9124 replied 7 years ago.

Ok, the code for the light would probably would have been, either P0455, P0446, P0449 or P0440 which refer to evap leak. which means the fuel tank is not holding the desired amount of fuel vapors. common causes are gas cap, vent sol. stuck open,purge valve and maybe a hose that is leaking fuel vapors. now the fuel gauge problem is most likely is a fuel level sensor in the tank, which will sometimes turn on the ses light and leave a code P0463. it may be a good idea to have the system scanned for codes. some of the auto parts will do free. like auto zone and some others. if you could have the system scanned for codes and post me back. I could give you a better idea what to repair. pretty sure you have a fuel gauge sensor in the tank going bad.


now the voltmeter, same goes here. have the electrical system checked. find out what the alt is putting out. amps and voltage.

Customer: replied 7 years ago.
Thank you for this advice. This vehicle still has the original battery. Could this have any bearing on any of these issues? Do you think the alternator is also failing?
Expert:  goodwrench9124 replied 7 years ago.
battery is a possibilty, alt is also a possiblity. there are some other things that can cause your problems. the dash cluster is always a possiblity. I have even seen a few ignition switchs cause some problems. that is why it is important to get some basic info first. trouble codes if any!! and a electrical test. but like i suspect, a fuel level sensor and a possible alt problem. if you get a code and post me back, I am sure we can help you save some money and get your vehicle fixed.
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