Fix P00B6: Mechanic’s Solutions That WORKED!

The OBD2 code P00B6: Radiator Coolant Temperature/Engine Coolant Temperature Correlation indicates a mismatch between the readings from the radiator coolant temperature sensor and the engine coolant temperature sensor.

This discrepancy can lead to issues like excessively rich exhaust, diminished fuel efficiency, drivability problems, and poor idle quality. Correctly diagnosing and addressing this issue is essential for ensuring the vehicle operates efficiently and maintains optimal engine performance.

P00B6 quick overview

Meaning	P00B6: Radiator Coolant Temperature/Engine Coolant Temperature Correlation
Is it serious?	Yes, it can significantly affect the vehicle’s performance and fuel efficiency.
Possible causes	– Faulty engine coolant temperature sensor – Faulty radiator coolant temperature sensor – Coolant level issues or overheating engine – Damaged wiring or connectors – PCM programming errors
How to diagnose?	Verify engine coolant level and check for overheating. Use a diagnostic scanner to compare data from both sensors. Inspect both sensors for damage or corrosion. Test circuits and connectors with a DVOM for electrical issues. Check PCM programming for any discrepancies.

How to fix P00B6 – learn from mechanics

I looked into P00B6 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: Chevrolet

Vehicle Information 2009 Chevrolet Silverado 1500 LT

Issue + Repair History

• Owner reported excessively rich exhaust and diminished fuel efficiency.
• No previous repairs mentioned.

Other OBD2 Codes + Test Results

• OBD2 Code: P00B6 (Radiator Coolant Temperature/Engine Coolant Temperature Correlation).
• Live data reveals a discrepancy between signals from the radiator coolant temperature sensor and the engine coolant temperature sensor.

Mechanic Suggestions

• Begin by verifying that the engine is full of coolant and not overheating under any circumstances.
• Use a diagnostic scanner to retrieve data from the engine coolant temperature sensor and the radiator coolant temperature sensor.
• Inspect the ECT sensor and radiator coolant temperature sensor for any signs of damage or corrosion.
• Test the circuits and connectors associated with both sensors for shorts or open circuits using a digital volt/ohmmeter (DVOM).
• Check for any PCM programming errors using a reliable source of vehicle information.

Final Fix Upon inspection, it was found that the engine coolant temperature sensor was faulty, leading to the discrepancy in signals and the P00B6 fault code. The faulty sensor was replaced with a new one, and the circuit connections were tested to ensure proper functionality. After the replacement of the engine coolant temperature sensor, the excessively rich exhaust and diminished fuel efficiency issues were resolved, restoring normal vehicle operation.

Case #2: Vauxhall

Vehicle Information 2012 Vauxhall Astra GTC

Issue + Repair History

• Owner complained of drivability issues and poor idle quality.
• No previous repairs mentioned.

Other OBD2 Codes + Test Results

• OBD2 Code: P00B6 (Radiator Coolant Temperature/Engine Coolant Temperature Correlation).
• Live data shows a significant difference between signals from the radiator coolant temperature sensor and the engine coolant temperature sensor.

Mechanic Suggestions

• Start by checking the coolant level and ensuring the engine is not overheating.
• Utilize a diagnostic scanner to gather data from both the engine coolant temperature sensor and the radiator coolant temperature sensor.
• Inspect the ECT sensor and radiator coolant temperature sensor for any signs of malfunction or damage.
• Test the circuits and connectors associated with both sensors using a digital volt/ohmmeter (DVOM) to identify any shorts or open circuits.
• Verify the PCM’s programming for any potential errors using reliable vehicle information sources.

Final Fix Upon inspection, it was discovered that the radiator coolant temperature sensor was faulty, leading to the discrepancy in signals and the P00B6 fault code. The faulty sensor was replaced with a new one, and thorough testing of the circuits was conducted to ensure proper operation. Following the replacement of the radiator coolant temperature sensor, the drivability issues and poor idle quality were resolved, restoring the vehicle’s performance to normal.

Case #3: Chevrolet

Vehicle Information 2015 Chevrolet Cruze LT

Issue + Repair History

• Experienced excessively rich exhaust and reduced fuel efficiency.
• No previous repairs mentioned.

Other OBD2 Codes + Test Results

• OBD2 Code: P00B6 (Radiator Coolant Temperature/Engine Coolant Temperature Correlation).
• Diagnostic scan revealed a discrepancy between signals from the radiator coolant temperature sensor and the engine coolant temperature sensor.

Mechanic Suggestions

• Begin by checking the coolant level and ensuring there are no signs of engine overheating.
• Utilize a diagnostic scanner to gather data from both the engine coolant temperature sensor and the radiator coolant temperature sensor.
• Inspect the ECT sensor and radiator coolant temperature sensor for any signs of malfunction or damage.
• Test the circuits and connectors associated with both sensors using a digital volt/ohmmeter (DVOM) to identify any shorts or open circuits.
• Verify the functionality of the PCM and ensure there are no programming errors using reliable vehicle information sources.

Final Fix After thorough inspection, it was determined that the radiator coolant temperature sensor was faulty, leading to the disparity in signals and the triggering of the P00B6 fault code. The faulty sensor was replaced with a new one, and extensive testing of the circuits was conducted to confirm proper operation. Following the replacement of the radiator coolant temperature sensor, the issues with the excessively rich exhaust and reduced fuel efficiency were successfully resolved, restoring the vehicle’s performance to optimal levels.

Diagnostic Step	Brief Explanation
Verify engine coolant level	Ensures the engine has sufficient coolant and isn’t overheating, which could skew sensor readings.
Use a diagnostic scanner	Compares readings from both the radiator and engine coolant temperature sensors for discrepancies.
Inspect both sensors	Checks for any physical damage or corrosion that might affect sensor accuracy.
Test circuits and connectors	Uses electrical tools to find any shorts or opens that could cause incorrect readings.
Check PCM programming	Ensures the vehicle’s computer is correctly interpreting the sensor data without errors.