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P00B7 Code – What Does It Mean & How To Fix It

This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.


P00B7 is an OBD-II Code that refers to Engine Coolant Flow Low/Performance


A P00B7 code means that a vehicle’s computer has detected a low engine coolant flow and the ECT (Engine coolant Temperature) sensor is sensing a temperature that is stuck below the minimum threshold. When this occurs, the vehicle’s computer will set a P00B7 code and turn on the Check engine light.


Common causes for this code include:

  • Low coolant 
  • Stuck thermostat
  • Defective ECT sensor 
  • Faulty radiator 
  • Coolant temperature sensor Shorted
  • Open circuits or connectors 
  • Bad PCM or programming error

Also Read: Why Is My Temperature Gauge Not Going Up?


The symptoms of a P00B7 code are:

  • Exhaust is excessively rich 
  • Drivability issues 
  • Bad idle
  • Reduced fuel efficiency


To diagnose a P00B7 DTC code, a technician would:

  1. Scan for codes 
  2. Look for symptoms 
  3. Examine cooling system hoses and connections 
  4. Test the thermostat with a multimeter 
  5. If no codes are found, test the engine coolant temperature sensor by monitoring it’s voltage using an oscilloscope or sampling tester.
  6. Replace components as necessary until P00B7 code is eliminated.

Common mistakes

The following are some of the most common mistakes that a technician may make when diagnosing a P00B7 code:

  • Not checking for additional codes 
  • Incorrectly testing a thermostat or ECT sensor 
  • Not verifying that the coolant system is filled to adequate level 
  • Assuming a new radiator will solve the issue without any further diagnosis
  • Replacing components without diagnostic test results

How serious is this?

A P00B7 code should be treated serious as it can become potentially dangerous if not fixed. It is important to get this code diagnosed and repaired as soon as possible to ensure proper vehicle operation.

What repairs can fix the code?

repair manuals

The following are solutions that may fix this problem:

  • Inspect and service cooling system 
  • Replace thermostat 
  • Repair or replace radiator if needed 
  • Repair open circuits/connections to ECT sensor
  • Replace ECT sensor
  • Re-flash the engine control module with updated software 
  • Clean or replace PCM if necessary 
  • Reset the Check Engine Light (CEL) and recheck for further issues

Related codes

A P00B7 is related to and may be accompanied by the following codes: 

P0123 – Thermostat Malfunction

P0088 – High Coolant Temperature 

P1280 – Radiator Outlet Temp Sensor Circuit Low Voltage

P1281 – Radiator Outlet Temp Sensor Circuit High Voltage


In conclusion, the P00B7 code is a generic trouble code that means the computer has detected an issue with the Engine Coolant Flow Low/Performance. This is harmful to the vehicle and should be diagnosed and repaired as soon as possible. The most common causes for this code include issues with the thermostat, ECT sensor, radiator, PCM programming error or a bad coolant temperature sensor. A technician will use their Scan Tool to diagnose each potential issue until they can find the cause of P00B7 DTC Code. If you are experiencing these symptoms, contact your local automotive service center to schedule an inspection.