Faulty radiator coolant temperature sensor; Damaged or corroded sensor electrical connector; Chafed, open, or shorted wiring in the sensor circuit; Coolant level low or air pockets around the sensor; Thermostat stuck open or closed affecting warm-up rate; Engine control module software or internal circuit fault

DTC codes / P00xx · Fuel and air metering and auxiliary emission controls / P00B2

P00B2Radiator Coolant Temperature Sensor Circuit Range/Performance

P00B2 means the engine computer has detected that the radiator coolant temperature sensor signal is outside the expected range or is not behaving rationally compared with other temperature inputs. The computer compares the sensor voltage against a plausible operating window and flags the code when the reading is too high, too low, or inconsistent during warm-up.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering and auxiliary emission controls

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
Electric radiator fan running continuously or not engaging at all
Temperature gauge reading abnormally high, low, or fluctuating
Poor fuel economy or rough running during cold starts
Overheating warning or reduced engine power in some vehicles
Incorrect climate control operation or cabin heat performance

Common causes, most likely first

Faulty radiator coolant temperature sensor
Damaged or corroded sensor electrical connector
Chafed, open, or shorted wiring in the sensor circuit
Coolant level low or air pockets around the sensor
Thermostat stuck open or closed affecting warm-up rate
Engine control module software or internal circuit fault

How to diagnose and fix it

Scan all modules and record freeze-frame data to confirm when the fault sets
Visually inspect the sensor connector and wiring for corrosion, chafing, or looseness
Measure sensor resistance with a multimeter and compare with a temperature chart
Check coolant level and bleed the cooling system to remove air pockets
Back-probe the sensor signal wire at the engine control module to verify continuity and voltage
Replace the radiator coolant temperature sensor if resistance is out of specification
Clear codes and perform a road test with live data to confirm the repair

Why the radiator sensor code misleads

A low coolant level or trapped air can cause the sensor to read erratically even when the sensor itself is perfectly good.
The radiator coolant temperature sensor is often confused with the engine coolant temperature sensor, but they serve different circuits and can set different codes.
A stuck-open thermostat can make the engine warm up too slowly, causing the computer to flag the sensor as irrational during a cold start.
Corroded terminals inside the connector often mimic a failed sensor, so always inspect the plug before replacing parts.
Some vehicles use the radiator sensor primarily for fan control, so a fault may not affect the dashboard gauge at all.

Can I keep driving with P00B2?

You can usually drive short distances at moderate speed, but avoid heavy loads, towing, or long trips until the fault is repaired. If the temperature gauge climbs into the red or you see an overheating warning, stop safely and shut the engine off immediately.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.