Fault code P00B2 – radiator coolant temperature sensor circuit range/performance

Fault code P00B2 is called “Radiator Coolant Temperature Sensor (CTS) Circuit Range/Performance” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.

Technical description and explained code P00B2

An OBD-II code P00B2 will appear on the radiator coolant temperature sensor circuit if the operating range does not match. This occurs when the PCM detects a voltage or resistance value that deviates in either direction from the design parameters. The deviation should be approximately 10% over a period of time.

The temperature sensors on modern engines are of the variable resistance type, which convert temperature into signal voltages. The colder the coolant in the radiator, the higher the resistance. As the coolant temperature increases, the resistance decreases, thereby increasing the signal voltage to the PCM.

It is rare for a vehicle to have only one coolant temperature sensor. In most cases, one sensor is used to control the thermometer. The other controls the electric radiator fan or the cold start valves in some older systems.

Some diesel engines may have a special coolant temperature sensor to control the glow plugs.

As a result, when the coolant temperature changes, the resistance changes and the PCM sees this. If the PCM detects a voltage condition that is not within the operating range, error P00B2 will be set.

Symptoms of vehicle malfunctions

The main signal that an error P00B2 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.

It can also be warning signs such as:

1. Check engine control lamp on the control panel will light up (the code will be recorded in the memory as a malfunction).
2. The engine stalls or starts badly (especially when starting cold).
3. Floating revolutions, as well as attempts to stall at idle.
4. Overheating of the vehicle engine.
5. Incorrect or false temperature readings.
6. Increased fuel consumption.
7. Black smoke coming out of the exhaust pipe, if the mixture is rich.
8. Increased NOx emissions may be seen with lean mixture.
9. Abnormal operation of the cooling fans.

Error P00B2 is not a serious error, the car will be able to start and continue. But it’s better to solve it as soon as possible, because improper heat exchange can lead to more serious consequences.

Factors that can cause this error code

The error code P00B2 can mean that one or more of the following problems have occurred:

• The radiator coolant temperature sensor (CTS) has failed.
• The sensor is dirty.
• Coolant temperature sensor circuit is broken.
• Coolant temperature sensor wiring harness or connector is damaged.
• Blown fuse.
• Leaking sensor o-ring or gasket.
• Sometimes faulty PCM is the cause.

How to fix or reset OBD-2 code P00B2

Some suggested steps for troubleshooting and fix the error code P00B2:

1. Read all stored data and error codes with an OBD-II scan tool. To find out when and under what circumstances error P00B2 appears.
2. Clear the error codes from the computer memory and test-drive the vehicle to find out if error P00B2 appears again.
3. Check the coolant level (engine should be cold).
4. Visually inspect the electrical wiring and connections relating to the sensor for looseness and damage. Repair as necessary.
5. If the CTS sensor has failed, replace it.
6. Inspect the fuse; if it is blown, replace it.
7. Clear the error code from the computer memory again, test drive the vehicle to see if the problem is resolved.

Diagnose and repair of problems

The first step in troubleshooting error P00B2, is to review the service bulletins (TSB). For known problems with a particular vehicle.

Perform a thorough visual inspection to check the wiring for obvious defects such as scratches, scuffs, exposed wires or burn spots. Next, check connectors and connections for safety, corrosion, and contact damage.

Be sure to carefully check the integrity of the wire harnesses and secure any loose wires. If you find a burned wire, solder it and make sure it is properly insulated.

Check coolant and thermostat

Make sure the coolant level is correct, both in the radiator (when cold) and in the coolant overflow tank. Make sure that there are no leaks and that the sealed cap is working properly.

If there is not enough coolant in the system, the engine may not warm up properly. Because if the temperature sensor is not in contact with the coolant, it will not read the temperature.

Using a non-contact thermometer, or a real-time streaming scan tool, check to see if the engine is warming up properly. Normally, the upper radiator hose should stay relatively cold until the thermostat opens. After that, it will warm up quickly.

If the thermostat is open, the coolant will leak constantly, preventing the engine from reaching operating temperature. This can also be the cause of fault code P00B2.

Use a thermometer or diagnostic tool to check the engine temperature after 10-15 minutes of operation. If the temperature does not reach the operating temperature, check the CTS sensor.

Check the coolant temperature sensor (CTS)

Visually check the sensor for wiring or connector damage and repair if necessary. Then connect an OBD2 scanner, if the radiator temperature is excessively high, about 284°F, this is not normal.

Disconnect the sensor and see if the reading drops, like 50°F. If it does, the sensor is probably faulty, shorted internally, causing a low resistance signal to be sent to the PCM.

But, if you want to be completely sure it’s the sensor and not the wiring, you can do a test. Check the resistance of the sensor against ground with an ohmmeter. The resistance of a normal sensor will vary slightly from car to car.

But basically, if the engine temperature is about 200 degrees Fahrenheit, the resistance will be about 200 ohms. At about 0°F, the resistance will be over 10,000 ohms.

With this test, you will be able to determine if the resistance of the sensor matches the temperature in the system. If it doesn’t match the radiator temperature, you probably have a faulty sensor.

On which vehicles does this problem occur most frequently

Fault code P00B2 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

• Acura
• BMW
• Chevrolet
• Ford
• Honda
• Mazda
• Mercedes-Benz
• Mini
• Nissan
• Vauxhall

Fault code P00B2 can sometimes be found with other errors. The most common are the following: P00B1, P00B3, P00B4, P00B5, P00B6.

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