P1290 Cylinder Head Overtemp Fail-Safe Cooling
The Powertrain Control Module (PCM) has detected that the cylinder head temperature has exceeded the calibrated maximum threshold via the Cylinder Head Temperature (CHT) sensor. As a protective measure, the fail-safe cooling strategy is activated, which alternately shuts off fuel injectors to pump air through the cylinders and reduce temperature. This results in severe power loss and rough engine operation.
01. Most Common Causes
- Low coolant level or cooling system leak
- Thermostat stuck closed
- Faulty water pump or damaged impeller
- Defective CHT sensor or shorted/open wiring
- Air pockets in cooling system due to improper bleeding
- Inoperative cooling fan (electric or viscous)
02. Symptoms You Will Notice
- Severe loss of engine power
- Rough running or misfire-like symptoms
- Engine overheating or high temperature gauge reading
- Check Engine Light illuminated
03. Step-by-Step Diagnosis
Check coolant level and inspect for leaks in hoses, radiator, and water pump.
Verify cooling fan operation and thermostat opening temperature.
Test CHT sensor resistance and compare to specifications; check wiring for shorts or opens.
Bleed cooling system to remove air pockets if low coolant or recent service.
Scan for additional codes and monitor CHT sensor data with a scan tool.
1. Frequently Asked Questions
Is it safe to drive?▼
No, driving with this code is not safe. The fail-safe cooling mode severely limits power and can cause engine damage if the underlying overheating issue is not addressed. Have the vehicle towed to a repair shop.
How much does it cost to fix?▼
Repair costs vary widely depending on the cause. A simple coolant top-off or sensor replacement may cost $100-$300, while a water pump or thermostat replacement can range from $300-$800. Major repairs like a head gasket or radiator replacement can exceed $1,000.