Cooling

P00B2 — Radiator Coolant Temperature Sensor Range/Performance

Severity: medium Drive with care, to a shop

What P00B2 means

The control module monitors a sensor that measures coolant temperature at the radiator outlet. It compares the reading with engine temperature and expected warm-up and cooling behavior. If the signal is stuck, jumpy, or disagrees with other data, P00B2 is stored. This data helps manage cooling fans and system monitoring.

Symptoms

  • Check Engine light on
  • Erratic or wrong temperature gauge readings
  • Cooling fans running at the wrong time or constantly
  • Reduced fuel economy
  • Rough idle
  • Overheating in traffic

Possible causes

  1. Failed radiator coolant temperature sensor
  2. Open, shorted, or chafed sensor wiring
  3. Corroded terminals or a loose connector
  4. Low coolant or air trapped in the system
  5. Faulty thermostat or poor coolant circulation
  6. Rarely, a control module fault

How to diagnose

  1. Scan for codes and freeze frame data, and look for other temperature or fan codes
  2. Check coolant level and condition on a cold engine and look for leaks
  3. Inspect the sensor, connector, and harness for corrosion, moisture, or damage
  4. Compare the sensor reading with the main engine coolant temperature sensor on a warm engine
  5. Measure sensor resistance and compare it with the spec at different temperatures
  6. Check 5 V reference and ground at the connector and test the wiring to the module
  7. Test the thermostat and cooling fan operation
  8. Verify actual radiator temperature with an infrared thermometer against the scan tool value

Common fixes

  • Replace the radiator coolant temperature sensor
  • Repair the wiring or replace the connector and clean the terminals
  • Top off coolant, fix leaks, and bleed air from the system
  • Replace a faulty thermostat
  • Reflash or replace the control module (rare)

Questions and answers

What does P00B2 mean?

The control module sees an implausible signal from the radiator outlet coolant temperature sensor. The usual culprits are the sensor itself, its wiring, or the connector.

Can I drive with P00B2?

For a short time, yes, while watching the temperature gauge. If the fans are controlled incorrectly, overheating is possible, so don't put off diagnosis.

How do I clear P00B2?

Fix the underlying problem first, then clear the code with a scan tool. If the fault remains, the code will return.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.