Radiator Coolant Temperature Sensor Circuit High
The P00B4 code indicates that the Engine Control Module (ECM) has detected a voltage signal from the radiator coolant temperature sensor that is higher than the expected range, typically above 4.5 volts. This sensor monitors the coolant temperature at the radiator outlet. A high voltage reading suggests an open circuit, a short to voltage, or a faulty sensor. The ECM uses this input for cooling fan control and transmission shift strategies, so an incorrect reading can lead to performance issues.
01. Most Common Causes
- Faulty radiator coolant temperature sensor
- Open or shorted wiring in the sensor circuit
- Poor electrical connection at the sensor connector
- Corroded terminals or damaged harness
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Engine overheating or cooling fans running constantly
- Poor fuel economy
- Transmission shifting issues
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and freeze frame data.
Step 2: Visually inspect the sensor and wiring for damage or corrosion.
Step 3: Test sensor resistance with a multimeter; compare to specifications.
Step 4: Check for voltage at the sensor connector (should be 5V reference).
Step 5: If sensor and wiring are okay, replace the sensor.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with this code as it can cause engine overheating or transmission damage. Have it diagnosed promptly.
How much does it cost to fix?▼
The typical repair cost ranges from $50 to $150, including parts and labor, depending on the vehicle and shop rates.