Service Information

Cruze

DTC P00B3 or P00B4

Diagnostic Instructions

•	Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

•	Review Strategy Based Diagnosis for an overview of the diagnostic approach.

•	Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P00B3 00: Radiator Coolant Temperature (RCT) Sensor Circuit Low Voltage

DTC P00B4 00: Radiator Coolant Temperature (RCT) Sensor Circuit High Voltage

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
RCT Sensor Signal	P00B3 00	P00B4 00	P00B4 00*	-
Low Reference	-	P00B4 00	P00B4 00*	-
*Engine control module (ECM) or sensor damage may occur if the circuit is shorted to B+

Typical Scan Tool Data

ECT Sensor 2

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: The ignition is ON, or the engine is running Parameter Normal Range: Varies with ambient temperature, within a range of -39 to +120°C (-38 to +248°F)
RCT Sensor Signal	150°C (302°F)	-40°C (-40°F)	-40°C (-40°F)
Low Reference	-	-40°C (-40°F)	-40°C (-40°F)

Circuit

Short to Ground

Open

Short to Voltage

Operating Conditions: The ignition is ON, or the engine is running

Parameter Normal Range: Varies with ambient temperature, within a range of -39 to +120°C (-38 to +248°F)

RCT Sensor Signal

150°C (302°F)

-40°C (-40°F)

Low Reference

-40°C (-40°F)

The radiator coolant temperature (RCT) sensor is a variable resistor that measures the temperature of the radiator coolant. The ECM supplies 5 V to the RCT sensor signal circuit and supplies a ground for the low reference circuit.

Conditions for Running the DTC

•	The ignition is ON, or the engine is running.

•	The battery voltage is greater than 9 V.

•	The intake air temperature (IAT) is warmer than -30°C (-22°F) or the IAT is colder than -30°C (-22°F) and the engine run time is greater than 120 s.

•	This DTC runs continuously within the enabling conditions.

Conditions for Setting the DTC

P00B3 00

The ECM detects that the RCT sensor signal is less than 0.27 V, which is warmer than 137°C (279°F) for greater than 2 s.

P00B4 00

The ECM detects that the RCT sensor signal is greater than 4.96 V, which is colder than-39°C (-38°F) for greater than 2 s.

Action Taken When the DTC Sets

•	DTCs P00B3 00 and P00B4 00 are Type B DTCs

•	The cooling fans will be commanded ON.

•	The A/C compressor will be commanded OFF.

Conditions for Clearing the DTC

DTCs P00B3 00 and P00B4 00 are Type B DTCs.

Reference Information

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

If the ignition has been OFF for 8 h or greater, the IAT, the ambient air temperature, and the RCT should be within 9°C (16°F) of each other. Ignition ON, observe the scan tool IAT Sensor, Ambient Air Temperature, and the ECT Sensor 2 parameters. Compare those sensor parameters to each other to determine if the condition is current.
Engine running, observe the ECT Sensor 2 parameter. The reading should be between -39 to +120°C (-38 to +248°F) depending on the current Ambient Air Temperature, the engine run time, and the vehicle operating conditions.
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

Ignition OFF, disconnect the harness connector at the B34B Engine Coolant Temperature Sensor 2.
Ignition OFF, test for less than 5 Ω between the low reference circuit terminal 2 and ground.

⇒	If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module.

Ignition ON, verify the scan tool Temperature is greater than 4.8 V.

⇒	If less than the specified range, test the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the K20 Engine Control Module.

Install a 3 A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 2. Verify the scan tool Temperature is less than 0.3 V.

⇒	If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module.

If all circuits test normal, test or replace the B34B Engine Coolant Temperature Sensor 2.

Component Testing

Static Test

Measure and record the resistance of the B34B Engine Coolant Temperature Sensor 2 at various ambient air temperatures, then compare those measurements to the Temperature Versus Resistance table.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Engine Control Module Replacement for ECM replacement, setup, and programming