Code 15 coolant sensor low on 1995 Saturn SL1

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I have been having problems with my rpms going hi and low and then high and low and dieing ive replaced several parts in cluding the coolant sensor and now that what my code is, so did i get a bad one my car was and it running pretty much the same way!
(1) Answer
Vehicle Application: 1995 SL Series 1.9

Customer Concern: Trouble code 15. New Coolant Temperature Sensor (CTS), same. Scanner shows CTS at -40F with a warm engine. Runs rough.

Tests/Procedures: 1. Disconnect the CTS connector. Check for 4.8 to 5.0 volts between the Yellow and Black CTS wires.

2. If not there, check for an open on the Yellow or Black wire to the Powertrain Control Module (PCM).

3. Check the new CTS for about 200-500 ohms resistance at warm operating temperature.

Could be a connector or wiring problem.