Cylinder Head Temp Sensor Out Of Self Test Range
Your engine's cylinder head temperature sensor is reading outside the expected range during self-test, like a thermometer giving wildly inaccurate readings. The ECU can't trust the temperature data, so it flags this fault to prevent engine damage from running too hot or cold.
The ECM monitors cylinder head temperature during engine startup and warm-up to ensure the sensor responds within expected voltage and temperature parameters. If the reading falls outside the calibrated self-test range—typically 32°F to 275°F (0°C to 135°C)—the ECU detects a sensor malfunction and stores this code.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Sensor Voltage | 0.5V to 4.5V during self-test | Outside 0.5V-4.5V range or no voltage change |
| Temperature Range | 32°F to 275°F (0°C to 135°C) | Below 32°F or above 275°F during warm-up |
Code P1293 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, P1293 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.