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  • DTC P00B7 stands for “Engine Coolant Flow Low/Performance.”
  • This code is logged when the PCM perceives insufficient coolant flow through the cooling system.
  • Code P00B7 is commonly caused by low coolant levels, faulty thermostats, bad water pumps, or malfunctioning ECT sensors.
  • Common symptoms to watch out for include an illuminated check engine light, overheating engine, and abnormal temperature gauge readings.

An OBD-II code is designed to alert you of the potential problems your car may have. To resolve it, you must first know what the logged code entails. If you’re finding it difficult to figure out what code P00B7 means, you’ve come to the right place. Read on to learn about its possible triggers and common symptoms.

What Does the P00B7 Code Mean?

Diagnostic trouble code (DTC) P00B7 stands for “Engine Coolant Flow Low/Performance.” This code is logged when the powertrain control module (PCM) perceives insufficient coolant flow through the cooling system.

coolant flow
Code P00B7 may register if the PCM perceives insufficient coolant flow through the cooling system.

This trouble code is set when the correlating signals between the engine coolant temperature (ECT) sensor and the radiator coolant temperature sensor (or secondary engine coolant temperature sensor) exceed the allowable threshold, which tends to happen if the ECM/PCM can’t control thermostat operation. The ECM/PCM perceives this discrepancy in signals as the result of a low or restricted engine coolant flow. In other words, the extra temperature sensor acts as part of a feedback loop to help the ECM/PCM control the thermostat, thereby also controlling engine temperature.

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The PCM monitors both sensors to determine if there is sufficient coolant flow to keep the engine at operating temperature.

When the PCM concludes that the coolant flow is too low because of this huge difference in temperature between the ECT sensor and the radiator coolant temperature sensor, the radiator fan(s) may be set to high. The PCM does this to prevent the overheating of the engine.

Take note that this code typically only appears on vehicles with electric thermostats. Electrically controlled thermostats use expanding wax like old thermostats did, but a heater coil surrounding the wax capsule controls the temperature of the wax, and the ECM/PCM modulates voltage to the heater coil to more closely control the thermostat’s regulation of coolant flow.

Of course, for this method of controlling the thermostat to work properly, the temperature of the coolant in the radiator must be monitored and compared to the temperature of the coolant in the block and the thermostat is triggered accordingly. If the heating coil fails, the thermostat will still operate the way older thermostats did, but the PCM has far less control of coolant temperature.

Note: The definition of code P00B7 may be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.

What are the Possible Causes of the P00B7 Code?

Here are some common triggers of the error code P00B7:

See also  Underhood Checks
water pump
A faulty water pump can trigger code P00B7.

What are the Common Symptoms of the P00B7 Code?

You may notice the following symptoms if you drive a car that has a logged P00B7 error code:

  • Illuminated check engine light
  • Overheating engine
  • Abnormal temperature gauge readings
  • Rough running
  • Poor fuel economy

How to Diagnose the P00B7 Code

To avoid complications, code P00B7 should be resolved immediately. However, diagnosing this code can be a struggle, as it has many possible triggers. To make sure you’re on the right path, the diagnostic and repair steps should always depend on the specifications of your vehicle.

Because all cars are built differently, they would also require different diagnoses. A P00B7 on a Chevy, for instance, may require a different diagnosis process from a P00B7 on a Honda. Refer to a repair manual specific to your vehicle for the appropriate automotive diagnostic steps.

However, if you feel like your automotive know-how is lacking, it would be best to let the professionals handle the diagnosis of this trouble code instead.

See also  P0306 Code: Cylinder 6 Misfire Detected

How to Fix the P00B7 Code

The P00B7 code may share similar triggers and symptoms with other DTCs. However, that does not mean it also shares their fixes. All vehicles are different, so you should always refer to the factory repair information specific to your car before DIY-ing any repairs.

Consult a repair manual or repair database before attempting any fixes. Look for confirmed solutions that are specific to your vehicle. If you aren’t confident in your automotive repair skills, it may be best to enlist the help of a professional.

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About The Authors
Richard McCuistian, ASE Certified Master Automobile Technician
Reviewed By Richard McCuistian, ASE Certified Master Automobile Technician

Technical Reviewer at

Richard McCuistian has worked for nearly 50 years in the automotive field as a professional technician, an instructor, and a freelance automotive writer for Motor Age, ACtion magazine, Power Stroke Registry, and others. Richard is ASE certified for more than 30 years in 10 categories, including L1 Advanced Engine Performance and Light Vehicle Diesel.

CarParts Research Team
Written By Research Team

Automotive and Tech Writers

The Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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