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 Descriptors
DTC P00B7
- Engine Coolant Flow Insufficient
Diagnostic Fault Information
Typical Scan Tool Data
Circuit Description
The engine control module (ECM) monitors the temperature of the engine radiator coolant. The ECM controls the thermostat with a pulse width modulated (PWM) signal. The ECM compares the radiator coolant temperature to the engine coolant temperature in order to determine if there sufficient coolant flow through the thermostat.
Conditions for Running the DTC
* DTCs P00B3, P00B4, P0117, P0118, P111E, and P112F are not set.
* The engine run time is greater than 5 m.
OR
* The engine coolant temperature is greater than 99°C (211°F).
* The DTC runs continuously when the above conditions are met.
Conditions for Setting the DTC
Note: The scan tool display range is between -40 and + 150°C (-40 and +302°F).
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 MIL/DTC
DTC P00B7 is a Type B DTC.
Diagnostic Aids
* The thermostat has a mechanical fail-safe in case of an electrical condition with the thermostat heater. The mechanical thermostat will start to open at approximately 97°C (206°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
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
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Verification
1. Ignition ON.
2. Verify that DTC P00B3, P00B4, P0480, P0481, P0597, P0598, or P0599 are not set.
• If DTC P00B3, P00B4, P0480, P0481, P0597, P0598, or P0599 are set
Refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle.
• If DTC P00B3, P00B4, P0480, P0481, P0597, P0598, or P0599 are not set
3. Verify the coolant in the radiator surge tank is at the correct level and there are no engine coolant leaks.
• If the coolant in the radiator surge tank is not at the correct level or there are engine coolant leaks
Refer to Cooling System Draining and Filling (GE 47716) Cooling System Draining and Filling (GE 47716)Cooling System Draining and Filling (Static Fill) Cooling System Draining and Filling (Static Fill) and Loss of Coolant Loss of Coolant.
• If the coolant in the radiator surge tank is at the correct level and there are no engine coolant leaks
4. Verify the engine cooling fan operates.
• If the engine cooling fan does not operate
Refer to Cooling Fan Inoperative Cooling Fan Inoperative.
• If the engine cooling fan operates
Note: Depending on ambient temperature, it may take up to 4 min for the temperature to decrease less than the specified value.
5. Engine idling for 15 min with the A/C OFF.
6. 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).
• If the temperature does not decrease to less than 85°C (185°F).
Refer to Circuit/System Testing.
• If the temperature does decrease to less than 85°C (185°F).
7. All OK.
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
• If a condition is found
Repair or replace the affected component as necessary.
• If no condition is found
2. Replace the E41 Engine Coolant Thermostat Heater.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
Engine Coolant Thermostat Housing Replacement (LUK) Service and RepairEngine Coolant Thermostat Housing Replacement (LCV) Service and RepairEngine Coolant Thermostat Housing Replacement (LTG) Service and Repair