Sensor/System Checks
- Check Mass Airflow (MAF) sensor and connections.
- Check the Engine Coolant Temperature (ECT) sensor for being shifted in value. Connect the scan tool and compare the ECT with the Intake Air Temperature (IAT) sensor on a cold engine. The ECT and IAT should be within 5°F of each other. Check the resistance of the ECT sensor if the temperature is out of range with the IAT sensor. See TEMPERATURE VS RESISTANCE
table for specifications.
- Check Throttle Position (TP) sensor and connections. See DTC P0121: THROTTLE POSITION SENSOR CIRCUIT INSUFFICIENT ACTIVITY
under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 4.0L AURORA article.
- Check for throttle body tampering, excessive deposits, or damage.
- Check the Exhaust Gas Recirculation (EGR) system for proper operation. See EXHAUST GAS RECIRCULATION
under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - 4.0L AURORA article.
TEMPERATURE VS RESISTANCE
| Temperature - °F (°C) |
Ohms |
| 302 (150) |
47 |
| 266 (130) |
77 |
| 230 (110) |
132 |
| 194 (90) |
241 |
| 158 (70) |
467 |
| 122 (50) |
973 |
| 104 (40) |
1459 |
| 86 (30) |
2238 |
| 68 (20) |
3520 |
| 50 (10) |
5670 |
| 32 (0) |
9420 |
| 14 (-10) |
16,180 |
| -4 (-20) |
28,680 |
| -40 (-40) |
100,700 |