What Does P0C74 Mean?
DTC P0C74 indicates that motor electronics coolant pump B is not performing within expected parameters. The control module has detected that the pump is not achieving the commanded flow rate or speed. Pump B typically serves a secondary cooling circuit or provides redundancy for critical power electronics cooling in hybrid and electric vehicles.
Safety Warning
Motor electronics overheating from inadequate coolant pump performance can cause the vehicle to enter a severe power-limited mode or shut down the electric drivetrain entirely. Prolonged overheating may cause permanent damage to expensive power electronics components.
Common Causes
30%
Failing coolant pump B motor (worn brushes, seized bearings, damaged impeller)
25%
Electrical fault in pump B control circuit (corroded connector, broken wire, high resistance)
20%
Restriction in the coolant loop (blocked heat exchanger, collapsed hose, air lock)
15%
Power electronics control module driver circuit fault for pump B
10%
Low coolant level or contaminated coolant reducing pump efficiency
Diagnostic Steps
1
Check coolant level in the motor electronics cooling loop and inspect for leaks.
2
Use the scan tool to command pump B on and off; verify audible operation and measure actual flow rate if possible.
3
Measure voltage, ground, and current draw at the pump B connector during operation and compare to specifications.
4
Inspect the wiring harness and connector to pump B for damage, corrosion, or loose terminal connections.
5
Bleed the cooling system to remove any air pockets and inspect hoses and heat exchangers for restrictions.
6
Replace pump B if electrical and mechanical tests confirm inadequate pump performance.
Estimated Repair Cost
$300 - $1,500
Parts + labor, varies by vehicle and location
DTC P0C74 indicates that motor electronics coolant pump B is not performing within expected parameters. The control module has detected that the pump is not achieving the commanded flow rate or speed. Pump B typically serves a secondary cooling circuit or provides redundancy for critical power elect...
The most common cause of P0C74 (Motor Electronics Coolant Pump "B" Control Performance) is: Failing coolant pump B motor (worn brushes, seized bearings, damaged impeller)
Typical repair costs for P0C74 range from $300 to $1,500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Motor electronics overheating from inadequate coolant pump performance can cause the vehicle to enter a severe power-limited mode or shut down the electric drivetrain entirely. Prolonged overheating may cause permanent damage to expensive power electronics components.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0C74 to identify the root cause.
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Quick Info
Category
Powertrain
System
Motor Electronics Thermal Management
Difficulty
Type
Generic (SAE)
Recommended Tools
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