Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Pinpoint Test DX: Engine Coolant Temperature (ECT) Sensor: Introduction: Notes
This pinpoint test is intended to diagnose the following:
- engine coolant temperature (ECT) sensor (12A648)
- harness circuits: ECT and SIGRTN
- powertrain control module (PCM) (12A650)
Engine coolant temperature must be greater than 10°C (50°F) to pass the KOEO self-test and greater than 82°C (180°F) to pass the KOER self-test. To accomplish this, the engine must be at normal operating temperature.
Voltage values calculated for VREF = 5 volts. These values can vary by 15% due to sensor and VREF variations.
| Temperature | Temperature Sensor Values | ||
|---|---|---|---|
| °C | °F | Voltage | Resistance (K ohms) |
| 120 | 248 | 0.28 | 1.18 |
| 110 | 230 | 0.36 | 1.55 |
| 100 | 212 | 0.47 | 2.07 |
| 90 | 194 | 0.61 | 2.80 |
| 80 | 176 | 0.80 | 3.84 |
| 70 | 158 | 1.05 | 5.37 |
| 60 | 140 | 1.37 | 7.70 |
| 50 | 122 | 1.77 | 10.97 |
| 40 | 104 | 2.23 | 16.15 |
| 30 | 86 | 2.74 | 24.27 |
| 20 | 68 | 3.26 | 37.30 |
| 10 | 50 | 3.73 | 58.75 |
| 0 | 32 | 4.14 | 95.85 |
| -10 | 14 | 4.45 | 160.31 |
NO RELATED
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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.