Engine Coolant Temp/Fuel Temp Correlation Issue
The P008F code indicates that the Engine Control Module (ECM) has detected a discrepancy between the engine coolant temperature (ECT) sensor and the fuel temperature sensor readings. This typically occurs when the sensors provide conflicting data, such as the coolant temperature being significantly higher or lower than the fuel temperature under certain conditions. The ECM uses both sensors for fuel trim and injection timing adjustments, so a correlation fault can lead to poor engine performance, increased emissions, and potential drivability issues.
01. Most Common Causes
- Faulty engine coolant temperature (ECT) sensor
- Faulty fuel temperature sensor
- Wiring or connector issues in the sensor circuits
- Incorrect coolant level or air in cooling system
- ECM software or calibration error
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Poor fuel economy
- Rough idle or hesitation
- Hard starting, especially when cold
- Engine overheating or running too cool
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and freeze frame data to confirm P008F.
Step 2: Visually inspect ECT and fuel temperature sensor connectors and wiring for damage or corrosion.
Step 3: Compare ECT and fuel temperature sensor readings using a scan tool; they should be similar when engine is cold.
Step 4: Test sensor resistance and voltage output per manufacturer specifications.
Step 5: Check coolant level and condition; bleed air from cooling system if necessary.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is generally not recommended to drive long distances with this code, as it can cause poor engine performance, reduced fuel economy, and potential overheating. Have it diagnosed promptly.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for diagnosis and sensor replacement, depending on labor rates and parts prices.