What Does P00B7 Mean?
The PCM has determined that engine coolant flow is below the expected rate or the cooling system is not performing adequately. This code may be set based on calculated coolant flow using temperature differentials between the ECT and RCT sensors, or via an actual coolant flow sensor. The driver may notice the engine running hotter than normal, especially in traffic, or slow warm-up times if the thermostat is stuck open.
Safety Warning
Do not continue driving if the engine temperature is climbing toward the red zone. Insufficient coolant flow can lead to rapid overheating, causing warped cylinder heads, blown head gaskets, or catastrophic engine failure. If the temperature gauge is normal, drive cautiously to a shop, but avoid heavy load, towing, or extended idling.
Common Causes
35%
Thermostat stuck closed or partially restricted, limiting flow through the radiator
25%
Failing water pump with worn impeller or cavitation
20%
Partially blocked radiator core (internal scale or debris)
10%
Air pocket or low coolant level disrupting circulation
10%
Collapsed or kinked lower radiator hose restricting flow
Diagnostic Steps
1
Monitor ECT and RCT sensor PIDs under load — if ECT rises significantly but RCT stays low, coolant is not flowing through the radiator, indicating a thermostat or flow restriction.
2
With the engine warm and running, squeeze the upper and lower radiator hoses — both should feel firm with pressure; a soft lower hose may be collapsing internally.
3
Use an infrared thermometer to scan across the radiator face — cold spots indicate internal blockage in those tubes.
4
Check coolant level and bleed the system of any air pockets using the manufacturer's prescribed bleed procedure (many vehicles have a bleed valve on the thermostat housing).
5
If thermostat and hoses are good, consider testing the water pump by watching for coolant circulation with the radiator cap off at idle (on applicable systems) — no visible flow at 2000 RPM suggests a stripped impeller.
6
On vehicles with an electric water pump, verify pump operation and commanded speed via scan data PIDs.
Estimated Repair Cost
$100 - $800
Parts + labor, varies by vehicle and location
The PCM has determined that engine coolant flow is below the expected rate or the cooling system is not performing adequately. This code may be set based on calculated coolant flow using temperature differentials between the ECT and RCT sensors, or via an actual coolant flow sensor. The driver may n...
The most common cause of P00B7 (Engine Coolant Flow Low/Performance) is: Thermostat stuck closed or partially restricted, limiting flow through the radiator
Typical repair costs for P00B7 range from $100 to $800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Do not continue driving if the engine temperature is climbing toward the red zone. Insufficient coolant flow can lead to rapid overheating, causing warped cylinder heads, blown head gaskets, or catastrophic engine failure. If the temperature gauge is normal, drive cautiously to a shop, but avoid heavy load, towing, or extended idling.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P00B7 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Powertrain
System
Engine Cooling System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
