Service Engine Soon (SES) Light - PO 128B Engine Temp
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My SES light was intermittent for about a week when a technician told me the engine thermostat was going bad. I drove with it for about a month longer when the light came on and stayed on--this was during the winter, since I was running the heater, I thought I'd be okay for a while longer. Last week I smelled an odd (smoky) smell when driving my child to school, but by the time I made it back home there was no smell, so I attributed it to all the other vehicles idling in the drop-off lanes. I took the vehicle in that day for a diagnostic and the result was "PO 128B ENGINE TEMP BEFORE REGULATING TEMP." They reset the light at the shop and said to come back if it came back on. I drove another 50 miles over the next 3 days, and it came back on shortly after I began driving 65 mph. I've been doing light driving in the car since then, but we notice a smoky smell this morning while driving to school, which I may once again be able to attribute to the TransAm that was revving its engine in front of me. Do I have much longer b4 I MUST take it in, and will it be expensive?
RepairPal Certified shops can diagnose and repair your 2004 GMC Envoy. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.
YOU SHOULD HAVE THE THERMOSTAT REPLACED. IT SHOULD COME AS AN ASSEMBLY WITH THE HOUSING AND TAKE ABOUT AN HOUR AND A HALF TO REPAIR. YOUR THERMOSTAT MAY BE STUCK OPEN OR BE OPENING TOO SOON CAUSING THE ENGINE TO RUN TOO COLD TOO LONG AND USE MORE FUEL THAN NORMAL. 95% OF THESE CODES ARE A FAULTY THERMOSTAT.
