Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1989 Pontiac Sunbird GT, 2D Convertible, 2.0 K, StandardFACTORY OEM SERVICE PROCEDURE
Code 15, Coolant Temp Sensor Signal Volt Hi: Notes
NOTE:
Test numbers refer to test numbers on diagnostic chart.
- This test checks to see if code was set as a result of a hard failure or intermittent condition. Code 15 will set if engine has been running for more than 50 seconds and signal voltage indicates a coolant temperature less than -22°F (-30°C).
- This test simulates conditions for a Code 14. If ECM recognizes low signal voltage and "scan" tester indicates high temperature, ECM and wiring are not at fault.
- This test will determine if there is a wiring problem or a faulty ECM. If circuit No. 452 is open, there may also be a Code 21 stored.
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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