Diagnostic Procedure

2003 Nissan-Datsun Frontier Base, StandardSECTION Diagnostic Procedure
  1. On 3.3L models, start engine and check cooling fan operation. If cooling fan operates, go to next step. If cooling fan does not operate, repair as necessary.
  2. On all models, pressure test cooling system and radiator cap. Check thermostat operation. Radiator cap relief pressure should be 8.6-14.2 psi (59-98 kPa). Thermostat opening temperature should be 180°F (82°C). Repair coolant leaks or replace radiator cap or thermostat as necessary. If no problems are found, go to next step.
  3. Remove ECT sensor, and place in heated water. For location, see Figure or Figure . Measure resistance between sensor terminals, with water at specified temperatures. See ENGINE COOLANT TEMPERATURE SENSOR RESISTANCE  table under DIAGNOSTIC PROCEDURE under DTC P0117: ENGINE COOLANT TEMPERATURE SENSOR CIRCUIT LOW INPUT OR DTC P0118: ENGINE COOLANT TEMPERATURE SENSOR CIRCUIT HIGH INPUT  . If resistance is not as specified, replace ECT sensor. If resistance is as specified, check for other possible causes of engine overheating and repair as necessary.
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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.