Radiator Coolant Temp vs Engine Coolant Temp Correlation Issue
The P00B6 code indicates a discrepancy between the radiator coolant temperature sensor and the engine coolant temperature sensor readings. The powertrain control module (PCM) monitors both sensors to ensure proper cooling system operation. When the readings differ by more than a calibrated threshold, typically due to a stuck thermostat, faulty sensor, or low coolant level, this code is set. This can lead to improper engine temperature regulation, reduced fuel efficiency, and potential engine damage if ignored.
1. Most Common Causes
- Stuck thermostat (open or closed)
- Faulty or out-of-range engine coolant temperature (ECT) sensor
- Faulty or out-of-range radiator coolant temperature (RCT) sensor
- Corroded or loose electrical connections at sensor connectors
- Short circuit or open circuit in sensor signal wiring
- Clogged radiator or restricted coolant flow
- Defective or worn water pump
- Coolant leak causing low level and uneven circulation
- Air pocket in the cooling system
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Engine overheating or running cooler than normal
- Poor fuel economy
- Erratic temperature gauge readings
- Coolant leaks
3. Step-by-Step Diagnosis
Step 1: Scan for additional codes and freeze frame data.
Step 2: Visually inspect coolant level and condition; check for leaks.
Step 3: Compare live data from both coolant temperature sensors using a scan tool.
Step 4: Test thermostat operation by monitoring temperature rise during warm-up.
Step 5: Check sensor wiring and connectors for damage or corrosion.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances, as the engine may overheat or run too cold, causing poor performance and potential damage. Have it diagnosed promptly.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for diagnosis and sensor replacement, but can be higher if the thermostat or other components need replacement.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.