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Home >> Volkswagen >> 1999 >> Cabrio GL, 2.0 B, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - 2.0L - Aba >> Diagnostic Tests >> DTC P0118: ECT Sensor Circuit High Input
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DTC P0118: ECT Sensor Circuit High Input

NOTE: DTC is set when Engine Coolant Temperature (ECT) sensor signal is too high. For connector terminal wire colors, see appropriate wiring diagram in WIRING DIAGRAMS article. For component locations, see appropriate illustration under COMPONENT LOCATIONS in SELF-DIAGNOSTICS - INTRODUCTION article.
NOTE: Before replacing any component, ensure all connectors at component and ECM are clean and tight. After making any repairs, disconnect ECM harness connector for 10 seconds, connect ECM harness connector and retest system. It is necessary to generate an ECM readiness code if ECM memory is cleared, battery voltage is disconnected or ECM is disconnected. Engine Control Module (ECM) and Throttle Valve Control Module (TVCM) must also be matched when either component is replaced or when TVCM is removed and reinstalled.
  1. Inspect ECT sensor harness connector for looseness and/or corrosion. If problem exists, repair as necessary and retest system. If problem does not exist, go to next step.
  2. Turn ignition off. Disconnect Engine Control Module (ECM) harness connector. Connect Test Box (VAG 1598/18) to ECM harness connector, but not to ECM. Measure resistance between sockets No. 14 and 33 at test box. Resistance should be 1500-2000 ohms at 86°F (30°C) and 275-375 ohms at 176°F (80°C). If resistance is as specified, go to step  6. If resistance is not as specified, go to next step.
  3. Disconnect ECT sensor harness connector. Measure resistance between terminal No. 3 at ECT sensor harness connector and socket No. 14 at test box. Resistance should be less than 1.5 ohms. If resistance is not as specified, repair open in wiring between ECT sensor and ECM. If resistance is as specified, go to next step.
  4. Measure resistance between terminal No. 1 at ECT sensor harness connector and socket No. 33 at test box. Resistance should be less than 1.5 ohms. If resistance is not as specified, repair open in wiring between ECT sensor and ECM. If resistance is as specified, go to next step.
  5. Measure resistance between terminal No. 3 at ECT sensor harness connector and socket No. 33 at test box. Resistance should be infinite. If resistance is as specified, go to next step. If resistance is not as specified, repair short to ground in wiring between ECT sensor and ECM.
  6. Carefully release cooling system pressure. Remove ECT sensor and plug opening. Measure resistance between terminals No. 1 and 3 at ECT sensor (component side). Cool sensor with a freeze spray. Resistance should increase without interruption. When sensor is heated, resistance should drop. If resistances are not as specified, replace ECT sensor. If resistances are as specified, replace ECM.
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