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Home >> Nissan-Datsun >> 2003 >> Sentra Limited >> Repair and Diagnosis >> External Pages >> Different car >> Section 68 (Engine Controls Self-Diagnostics - Pathfinder & QX4) >> Diagnostic Tests >> DTC P0117: Engine Coolant Temperature Sensor - Low Input Or DTC P0118: Engine Coolant Temperature Sensor - High Input >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Nissan Pathfinder and 2002 Infiniti QX4. However, it is still accessible from the selected car via links, so may be relevant.
  1. Turn ignition off. Disconnect ECT sensor sub-harness connector. ECT sensor is located left side if engine block. See Fig 1 . Turn ignition on. Measure voltage between ground and ECT sensor sub-harness connector terminal No. 3 (Light Green/Red wire). Voltage should be about 5 volts. If voltage is as specified, leave harness connector disconnected and go to step  3 . If voltage is not as specified, go to next step.
  2. Check following:
    • Check for poor, loose, corroded or damaged terminal connections in ECT sensor sub-harness connector.
    • Check for open or short in circuits between ECM and ECT sensor sub-harness connector. See WIRING DIAGRAMS article.
    If problem is found, repair as necessary. If no problem is found, go to next step.
  3. Turn ignition off. Check continuity between engine ground and ECT sensor sub-harness connector terminal No. 2 (Black wire). Continuity should exist. Also check circuit for short to voltage. See WIRING DIAGRAMS article. If no problem is found, go to step  5 . If problem is found, go to next step.
  4. Check for open in circuits between TCM and ECT sensor sub-harness connector. If problem is found, repair as necessary. If no problem is found, go to next step.
  5. Remove ECT sensor from engine. Place ECT sensor in heated water. Measure resistance between sensor terminals No. 2 and 3, with water at specified temperatures. See ENGINE COOLANT TEMPERATURE SENSOR RESISTANCE  table. If resistance is as specified, go to next step. If resistance is not as specified, replace ECT sensor and retest system.
    ENGINE COOLANT TEMPERATURE SENSOR RESISTANCE

    Temperature - °F (°C) (1) Ohms
    68 (20) 2100-2900
    122 (50) 680-1000
    194 (90) 236-260
    (1) Resistance should decrease as temperature increases. See Figure .
  6. Recheck following:
    • Check for poor, loose, corroded or damaged terminal connections in ECT sensor sub-harness connector.
    • Check for open or short in circuits between ECM and ECT sensor sub-harness connector. See WIRING DIAGRAMS article.
    If problem is found, repair as necessary. If no problem is found, go to next step.
  7. No problem is indicated at this time. Problem may be intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.
Fig 1: Locating Engine Coolant Temperature Sensor Sub-Harness Connector
G00025055Courtesy of NISSAN MOTOR CO., U.S.A.
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