Diagnostic Aids

WARNING: This page does not describe the selected car, but rather 32 other vehicles, including the 2003 Mercury Sable, 2003 Mercury Mountaineer, 2003 Mercury Marauder, 2003 Mercury Grand Marquis, and 2003 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.

Perform this test only when directed by QUICK TEST. Engine coolant temperature and engine oil temperature must be more than 50°F (10°C) to pass KOEO SELF-TEST and more than 180°F (82°C) to pass KOER SELF-TEST. Ambient air temperature must be at least 50°F (10°C) to receive valid input from Intake Air Temperature (IAT) sensor. Engine oil temperature must be more than 50°F (10°C) to pass KOEO SELF-TEST and more than 180°F (82°C) to pass KOER SELF-TEST. Voltage values in this test are based on a 5-volt VREF signal. Values may vary up to 15 percent due to sensor and VREF variations.

This system test is intended to diagnose the following components and circuits:

Intake Air Temperature (IAT) Sensor Or Integrated Intake Air Temperature (IAT) Sensor
MAF With Integrated Intake Air Temperature (IAT) Sensor.
Engine Coolant Temperature (ECT) Or Cylinder Head Temperature (CHT) Sensor
Engine Oil Temperature (EOT) Sensor
Wiring Harness Circuits (IAT, ECT, EOT & SIG RTN)
Powertrain Control Module (PCM)

To prevent replacing good components, ensure the following non-EEC areas or components are not cause of concern:

Coolant Level Low
Cooling System, Water Pump Or Fan
Engine Operating Temperature
Engine Oil Level Low
Thermostat
Air Cleaner Duct
Ambient Temperature

NOTE: On some models, IAT sensor is part of Mass Airflow (MAF) sensor assembly. If all 6 terminals of MAF sensor connector are being used, IAT sensor is integral to MAF sensor. See WIRING DIAGRAMS .