P00B6 Radiator Coolant Temperature/Engine Coolant Temperature Correlation
OBD-II Trouble Code Technical Description
Radiator Coolant Temperature/Engine Coolant Temperature Correlation
What does that mean?
This generic powertrain diagnostic trouble code (DTC) typically applies to many OBD-II vehicles. That may include many automakers but anecdotally this DTC seems more common on Chevrolet/Chevy and Vauxhall vehicles.
Anytime that I have been faced with diagnosing a code P00B6, it has meant that the powertrain control module (PCM) had detected a discrepancy in the correlating signals between the radiator coolant temperature sensor and the engine coolant temperature (ECT) sensor.
In order to make sure that coolant is flowing as intended between the radiator and the engine cooling passages, coolant temperature in the radiator is sometimes monitored in comparison with the temperature of coolant in the engine.
ECT sensor design usually consists of a thermal resistor that is dipped in a hard resin and sealed in a metal or plastic housing. Brass is the most popular of these housing materials because of its durability. In most cases, the ECT sensor is threaded so that it may be screwed into a coolant passage in the engine intake manifold, cylinder head, or block. The level of thermal resistance in the ECT sensor decreases as coolant warms and flows across it. This leads to increased ECT sensor circuit voltage at the PCM. As the engine cools, sensor resistance increases and ECT sensor circuit voltage (to the PCM) is reduced as a result. The PCM recognizes these fluctuations in voltage as changes in engine coolant temperature. Fuel delivery and ignition timing strategy are among the functions affected by actual engine coolant temperature and input data from the ECT sensor.
The radiator coolant temperature sensor monitors coolant temperature in much the same manner as the ECT sensor. It is typically inserted into one of the radiator tanks but may also be fitted into a pressurized coolant reservoir.
If the PCM detects voltage signals from the ECT sensor and the radiator coolant temperature sensor which differ from one another by greater than the maximum allowable parameter, a code P00B6 will be stored and a malfunction indicator lamp (MIL) may be illuminated. Multiple drive cycles with a failure may be required for MIL illumination.
An example of a radiator coolant temperature sensor:
What is the severity of this DTC?
As ECT sensor input is critical to fuel delivery and ignition timing strategy, the conditions that contribute to a stored code P00B6 should be addressed with urgency.
What are some of the symptoms of the code?
Symptoms of a P00B6 engine code may include:
Excessively rich exhaust Drivability issues Poor idle quality Seriously diminished fuel efficiencyWhat are some of the common causes of the code?
Causes for this engine code may include:
Defective ECT sensor Faulty radiator coolant temperature sensor Insufficient coolant level Shorted or open circuits or connectors Bad PCM or PCM programming errorWhat are some P00B6 troubleshooting steps?
An effort should be made to ensure that the engine is full of coolant and not overheating before attempting to diagnose any stored ECT sensor related codes. Before proceeding, the engine must be full of the proper coolant and not overheating under any circumstances.
A source of reliable vehicle information, a diagnostic scanner, a digital volt/ohmmeter (DVOM), and an infrared thermometer with a laser pointer will be required to diagnose a code P00B6.
A visual inspection of ECT sensor and radiator coolant temperature sensor system wiring and connectors should be your next step if the engine is not overheating,.
Prepare to retrieve all stored codes and freeze frame data by connecting the scanner to the ve
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