P00B7
DTC P00B7
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC P00B7
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Engine Coolant Flow Insufficient
Circuit/System Description
The engine control module (ECM) monitors the temperature of the radiator coolant temperature (RCT) sensor. The engine coolant thermostat heater is controlled by the ECM. The ECM controls the engine coolant thermostat heater with a pulse width modulated (PWM) signal. The ECM compares the radiator coolant temperature (RCT) sensor to the engine coolant temperature (ECT) sensor in order to regulate coolant flow through the radiator.
Conditions for Running the DTC
* DTCs P00B3 or P00B4 are not set.
* The engine run time is greater than 30 s.
* The engine coolant temperature (ECT) sensor is greater than 117°C (243°F) and the difference between engine coolant temperature (ECT) sensor 1 and engine coolant temperature sensor 2 is greater than 30°C (86°F).
* The DTC runs once per ignition cycle when the above conditions are met.
Conditions for Setting the DTC
The ECM detects the difference between the RCT sensor and the ECT sensor is greater than 30°C (86°F) when the ECT sensor is warmer than 117°C (242°F) for greater than 5 s.
Action Taken When the DTC Sets
DTC P00B7 is a Type B DTC.
Conditions for Clearing the DTC
DTC P00B7 is a Type B DTC.
Diagnostic Aids
* The engine coolant thermostat heater has a mechanical fail-safe in case of an electrical condition with the thermostat heater. The mechanical thermostat will open at approximately 104°C (220°F). The mechanical thermostat will cycle from approximately 104°C (220°F) to approximately 98°C (208°F).
* A resistance condition in the RCT sensor circuits may cause this DTC. This condition results in a greater voltage on the RCT sensor signal circuit, which is interpreted by the ECM as a colder RCT.
Reference Information
Schematic Reference
* Engine Controls Schematics [1][2]Electrical Diagrams for the LUW engine
* Engine Controls Schematics [1][2]Electrical Diagrams for the LUV engine
Connector End View Reference
Component Connector End Views Fuel Pump and Level Sensor Assembly
Description and Operation
Cooling System Description and Operation Description and Operation
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Verification
1. Ignition ON, observe the DTC information with a scan tool. DTC P00B3, P00B4, P0117, P0118, P0480, P0481, P0597, P0598, or P0599 should not be set.
• If a DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle.
2. Verify the coolant in the radiator surge tank is at the correct level and there are no engine coolant leaks. Refer to Cooling System Draining and Filling Cooling System Draining and Filling and Loss of Coolant Loss of Coolant.
3. Verify the engine cooling fan operates. Refer to Cooling Fan Always On (LUV LUW) Cooling Fan Always On (LUV LUW) and Cooling Fan Inoperative (LUW) Cooling Fan Inoperative (LUW)Cooling Fan Inoperative (LUV) .
Note:
Depending on ambient temperature, it may take up to 4 min for the temperature to decrease less than the specified value.
4. Engine idling for 15 min with the A/C OFF.
5. Command the Engine Coolant Thermostat Heater to 100% with a scan tool. Increase the engine speed to 3 000 RPM. Observe the scan tool ECT sensor parameters. The temperature should decrease to less than 85°C (185°F).
6. Operate the vehicle within the conditions for running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the freeze frame/failure records data.
Circuit/System Testing
1. Ignition OFF, inspect the cooling system for the following conditions:
* Weak coolant solution
* Obstructed radiator air flow or bent radiator fins
* Blocked cooling system passages
* Radiator hoses that are restricted, collapsed, or deteriorated
* Damaged water pump
* Loss of cooling system pressure
* Leaking surge tank cap
* Leaking radiator hoses
* Cylinder head or an engine block that is cracked or plugged
2. If you find any of the above conditions, repair as necessary.
3. If all conditions test normal, replace the E41 Engine Coolant Thermostat Heater.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Engine Coolant Thermostat Replacement (LUV) Engine Coolant Thermostat Replacement (LUW) Service and Repair
* Control Module References Control Module References for ECM replacement, programming and setup