P26D2

Code

Generic P — Powertrain

Engine Coolant Pump Control Module Over Temperature

Brand: Generic

Type: P — Powertrain

Views: UK: 23 EN: 39 RU: 24

AI status

Completed

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Page language: EN

Causes

Control module internal overheating (electronic component failure)
Excessive current draw from the coolant pump (mechanical binding or short)
Poor ventilation or cooling around the pump control module
High ambient under-hood temperatures or blocked airflow
Corroded/loose wiring or connector causing resistance heating
Short circuit in pump supply or control circuit

Symptoms

DTC P26D2 stored; MIL may or may not be illuminated depending on strategy
Reduced or disabled coolant pump operation (loss of electric coolant pump function)
Engine running hotter than normal or cooling system warnings
Intermittent or permanent cooling-related limp-home modes
Burnt smell or visible heat damage near pump/control module
Erratic coolant temperature readings or fan operation

What to check

Read and record freeze-frame and any related codes (ECT sensors, fan codes)
Visual inspection of pump, control module, connectors, and wiring for heat damage, corrosion, melted insulation
Check coolant level and condition; inspect for leaks
Check engine cooling fan operation and airflow near control module
Verify fuses and relays for pump power and control circuits
Measure pump supply voltage and observe pump current draw during operation

Signal parameters

Battery/supply voltage to pump/control module: typically 11–15 V during cranking/normal operation
Expected pump control PWM duty: 0–100% (varies by vehicle; should respond smoothly to commands)
Typical pump operating current (general range): ~3–25 A depending on pump design — abnormal high current suggests mechanical load or electrical short
Module internal temperature: normally below ~100–120 °C; DTC triggered when module temp exceeds manufacturer threshold (varies by design)
Cooling fan operation: on/off or variable as commanded; fans should engage when commanded to help cool area
Connector/wiring resistance: low continuity; high resistance indicates heating risk (no more than a few ohms in power feed)

Diagnostic algorithm

Connect a professional scan tool. Read and record P26D2 and any other stored codes, freeze frame, and live data (pump current, module temperature, coolant temp, fan state).
Perform a visual inspection of the coolant pump, control module, mounting, harness, and connectors. Look for melted plastic, discolored wiring, or burn marks.
Verify coolant level and inspect for leaks. Low coolant or air in the system can increase thermal load on the pump assembly.
With ignition ON (engine off) check supply voltage at the pump/control module harness; it should be within battery voltage limits. Inspect fuses/relays and their fuse ratings.
Start the engine and command the pump ON via scan tool (if supported) while monitoring supply voltage, pump current, PWM duty, and module temperature. Note any abnormal high current or failure to modulate.
If pump current is high, disconnect pump connector and check pump rotor for mechanical binding (bench test pump if possible) and measure current draw directly. Replace pump if mechanically seized or draws excessive current.
If pump current is normal but module temperature still exceeds threshold, check local airflow and cooling fan operation. Repair fan(s) or remove obstructions as required.
Check harness continuity and resistance between the module and power/ground/ECM. Repair any high-resistance connections, corroded pins, or poor grounds.
If wiring and pump test good, suspect internal module failure. Verify software/calibration updates with manufacturer; if none or if update doesn't clear problem, replace control module and re-test.
After repairs, clear codes and perform road/thermal test to confirm the module stays within temperature limits and the code does not return.

Likely causes

Pump current draw too high due to failing pump (bearing/seizure)
Faulty pump control module electronics failing thermal regulation
Poor connector/wiring condition causing local heating
Cooling fan failure or restricted airflow raising ambient module temp

Fault status

⚠️ Status

Engine Coolant Pump Control Module Over Temperature — control module temperature exceeded its allowed operating limit; module has logged an over-temperature fault.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-3.0 hours