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joe, Saturn Technician
Category: Saturn
Satisfied Customers: 722
Experience:  23+ years in the automotive repair business
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Saturn SL Series (?): 1999 Saturn (SL possibly, no letters

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1999 Saturn (SL possibly, no letters on car). After recent service prior to Calif. smog certification the car would not smog because the computers did not reset or were, for other reasons, not readable by the smog equipment. We were told that it needed to be driven for a while to reset the computer, but after several weeks of driving it was still not connecting to the smog tester machine. A code was found and cleared. We were told this code could block reset and we should drive it for a bit then retest. After several more weeks of driving it would not test. Took it back to the mechanic today, no codes were detected. We have tryed more than one test place. All say they tester cannot be read by the smog machine. When we had the car serviced, tune up, plugs etc, the only functional issue the mechanic commented on was the car ran cold. He thought a new thermostat may fix that but we did not change this. The comments from the smog test places has been on little help although one of them, who owned a saturn, said that temperature sensors may be an issue - not certain however.

We need help!!

Hello and thank you for using just answer! I am here to help you with your problem, so feel free to ask questions until you are satisfied.

Very common issue with saturn and emissions testing/state inspections, I see it all the time. The engine needs to meet certain criteria in order to be "ready" to pass the emissions test. One of the criteria is that the engine must maintain operating temperature throughout the drive cycle. The thermostat and coolant temperature sensor are known failures on these vehicles. The thermostat sticks open slightly..just enough to prevent the engine from reaching full operating temperature, but causes no driveability issues. Replace the thermostat and coolant sensor, drive the car for about 40 miles and you should be good to go.

Customer: replied 4 years ago.

This agrees with our mechanics observation of the engine running cool, although he was not aware of temp causing this issue.



OK good, keep me posted on th progress of the car. Please don't forget to rate my answer, or continue asking questions until you are satisfied.


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