P2B6B

Code

Generic P — Powertrain

Coolant Pump D Control Module Overtemperature

Brand: Generic

Type: P — Powertrain

Views: UK: 25 EN: 35 RU: 24

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Page language: EN

Causes

Excessive ambient temperature or restricted airflow around the control module
High electrical current draw from the coolant pump (stuck/binding pump or hydraulic restriction)
Low coolant level or poor coolant circulation causing extended pump operation
Poor electrical connections, corroded connector, or high resistance ground
Short to battery or load on the pump circuit increasing heat in the module
Internal fault or age-related degradation of the pump control module

Symptoms

Malfunction Indicator Lamp (MIL) or coolant system warning lamp illuminated
Reduced or no operation of Coolant Pump D (intermittent or permanent)
Engine running hotter than normal or occasional overheating
Reduced HVAC/Cabin heating or cooling performance if pump affects heater circuit
Stored DTC P2B6B and possibly related pump/control module codes

What to check

Read freeze frame and all stored/related codes with a capable scanner; record conditions
Visual inspection of coolant pump D, wiring harness, connectors and module for damage or corrosion
Confirm coolant level and look for leaks or blocked hoses that could increase pump load
Check module mounting and cooling (airflow, heatsink, thermal pads) for obstruction
Measure pump motor resistance and compare to specification
Measure pump current draw while operating (clamp meter) and compare to spec

Signal parameters

Battery/supply voltage at pump control module (V)
Pump control module internal temperature or thermal sensor reading (°C/°F)
Pump motor current draw (A)
PWM duty cycle or command percentage to pump (%)
Pump speed or flow if available (rpm or l/min)
Engine coolant temperature (ECT) and ambient air temperature

Diagnostic algorithm

Record stored codes and freeze-frame data. Do not rely on a single key-on event; confirm the failure is repeatable.
Allow vehicle to cool before touching cooling system components. Use appropriate PPE.
Perform a visual inspection: look for damaged wiring, loose connectors, corrosion, missing module heatsink or obstructed airflow.
Verify coolant level and inspect for restricted hoses, collapsed lines, or blockages that would increase pump load.
With a multimeter, check supply voltage and ground quality at the pump control module connector. Repair any poor connections.
Measure pump motor DC resistance (with disconnected connector) and compare to spec; excessive low resistance may indicate short/high current draw.
With the engine idling or as specified by manufacturer, use a clamp ammeter to measure actual pump current while commanding the pump on via scan tool. High current suggests binding or hydraulic restriction.
Command the pump on/off with a scan tool and monitor module temperature/overtemp status and PWM command. If module temperature rises rapidly with normal current, suspect internal module overheating or poor thermal coupling.
Inspect and restore any compromised thermal interface (heatsink, mounting) if applicable; ensure module mounting is secure and has adequate airflow.
If wiring, pump motor, coolant flow and mounting are good but overtemperature reoccurs, consider replacing the pump control module and then clear codes and road-test to confirm repair.
After repairs, clear codes and recheck. If fault returns, capture freeze-frame and consider module bench testing or manufacturer-specific technical service information (TSB/software updates).