Faulty radiator coolant temperature sensor drifting or sticking; Damaged wiring, corroded terminals or poor connector contact in the sensor circuit; Low coolant level or air in the cooling system giving false readings; Thermostat stuck open or closed so coolant temperatures disagree with expected values; Fault with the engine coolant temperature sensor, which the control unit uses to compare readings; Fault in the engine control unit or its software calibration (model-specific).

P00B2

Radiator Coolant Temperature Sensor Circuit Range/Performance.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
0: AreaFuel and air metering, auxiliary emission controls
B2: FaultThe specific fault in that area

What it means

P00B2 is the generic code for a radiator coolant temperature sensor circuit range or performance fault. The control unit has seen a signal from this sensor that is implausible, such as a reading that does not change as expected, stays stuck, or disagrees with the engine coolant temperature sensor or the modelled temperature. It is not a hard electrical open or short, which would normally set a separate circuit code. Whether the car has this sensor, and where it sits, depends on the model and engine.

Symptoms

Engine warning light on
Temperature gauge reading oddly, erratic or slow to respond
Cooling fans running constantly or at the wrong time
Poor fuel economy or rough running in some cases
Slow warm-up or heater output not as expected
Possible reduced performance if the control unit enters a default strategy

Possible causes

Faulty radiator coolant temperature sensor drifting or stickinglikely
Damaged wiring, corroded terminals or poor connector contact in the sensor circuitlikely
Low coolant level or air in the cooling system giving false readingspossible
Thermostat stuck open or closed so coolant temperatures disagree with expected valuespossible
Fault with the engine coolant temperature sensor, which the control unit uses to compare readingspossible
Fault in the engine control unit or its software calibration (model-specific)rare

How to diagnose

Read all stored and pending codes and note any other coolant temperature or thermostat codes
Review freeze frame data to see coolant temperature, engine load and running time when the code set
Check the coolant level when the engine is cold and look for leaks, air locks or contamination
Inspect the sensor, its wiring and connector for damage, corrosion, water ingress or chafing
Compare live data from the radiator and engine coolant temperature sensors on a cold engine, which should be close to each other and to ambient temperature
Watch live readings during warm-up to see if the radiator sensor responds smoothly and plausibly, and check the thermostat is opening at the correct temperature
Measure sensor resistance and circuit voltage against the manufacturer's specification for that model
Check for software updates or technical bulletins for the vehicle if all else tests good

How to fix

Replace the radiator coolant temperature sensor if it fails resistance or live data checks
Repair or replace damaged wiring and clean or renew faulty connector terminals
Top up and bleed the cooling system correctly, and repair any leak found
Replace a faulty thermostat
Replace the engine coolant temperature sensor if it is found to be at fault
Update the control unit software only if the manufacturer lists an outdated calibration as a known cause

Can I keep driving?

Medium severity

The car can usually be driven for a short time, but get it checked soon because incorrect temperature readings may affect fan control and engine protection. Stop and investigate if the temperature gauge rises or a coolant warning appears.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.