A/C Evaporator Air Temperature Circuit Range/Performance
Your air conditioning evaporator temperature sensor isn't reading properly or is stuck outside normal range, like a thermometer that's broken and giving wrong readings. The ECU can't verify if the A/C evaporator is cooling as expected.
The ECU monitors the evaporator temperature sensor (thermistor) to verify proper A/C cooling performance. It compares the voltage signal to expected temperature ranges and detects if the sensor reads too high, too low, or fails to change appropriately during A/C operation.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Evaporator Temperature Sensor Voltage | 0.5–4.5V corresponding to 32–65°F (0–18°C) | Out of range or static/unchanging for extended period |
| Temperature Rate of Change | Gradual cooling when compressor engages | No change or erratic fluctuation indicating sensor failure |
Code P1442 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P1442 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.