Cylinder Head Overtemperature Protection Active
Your engine is running too hot and the ECU has activated a protective shutdown mode to prevent damage, similar to how a computer throttles its processor when overheating. The engine will run in a limited-power state until temperatures return to normal.
The ECU monitors cylinder head temperature via the coolant temperature sensor and compares it against a high-temperature threshold. When the cylinder head temperature exceeds the protection limit, the ECU retards ignition timing and reduces fuel injection to cool the engine and prevent detonation or head damage.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Cylinder Head Temperature | 180-210°F (82-99°C) | >230°F (>110°C) triggers limp mode |
| ECU Protection Mode | Normal timing and fuel delivery | Retarded ignition and lean fuel mixture |
Code P1304 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, P1304 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.