P0CFF

Code

Generic P — Powertrain

Hybrid/EV Battery Pack Coolant Pump A Stuck/Stalled

Brand: Generic

Type: P — Powertrain

Views: UK: 26 EN: 28 RU: 34

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Page language: EN

Causes

Pump impeller mechanically jammed or seized
Debris or frozen/gelled coolant obstructing flow
Electrical supply fault to the pump (open, short, poor ground)
Pump driver/relay/fuse failure or PWM control fault
Connector corrosion, loose pins, or water ingress
Airlock in coolant circuit or blocked hose/radiator

Symptoms

DTC P0CFF present in scan tool/fault memory
Battery pack temperature rising or uneven cell temps
Reduced charge/discharge power or limp-home mode initiated by vehicle control system
Coolant leak or visible debris near pump area (sometimes)
Pump not audible when commanded or unusual noise from pump area
Heater/A/C performance for thermal management may be affected

What to check

Safely follow manufacturer high-voltage isolation procedures before touching high-voltage components; only qualified personnel should work on HV systems
Read freeze-frame and live data with a capable scan tool: pump command, pump status, battery pack temperature and cooling system temps/pressures
Perform visual inspection of pump assembly, harness, connector(s), fuse(s), and relay(s) for damage, corrosion, or water ingress
Check for coolant contamination, debris, or ice in areas around the pump, strainer, hoses and radiator
Verify pump supply fuse and relay operation (inspect and test)
Measure DC supply voltage at pump connector while pump is commanded on (observe safety precautions)

Signal parameters

Control command: PWM or switched DC from battery-management/control module (duty cycle varies with demand)
Expected nominal supply for auxiliary pumps: typically ~12–14 V DC for low-voltage pumps (vehicle-specific) — verify with manufacturer data
Typical running current: low-voltage pumps often draw ~0.5–8 A; high load or seizure will cause higher-than-normal current (compare to spec)
Pump feedback (if provided): tachometer or hall sensor pulses or presence/absence status bit — expected pulses when commanded
Thermal/pressure readings: coolant temperature and system pressure should change when pump runs

Diagnostic algorithm

Safety first: De-energize and isolate the high-voltage system per manufacturer procedure before any intrusive work on HV plumbing or electrical parts. Use PPE and follow shop safety rules.
Retrieve and record freeze-frame data and history from the BCM/BMS or hybrid control module. Note operating conditions when the code set.
Visually inspect pump, connectors, wiring harness, fuses, relays and adjacent coolant lines for damage, corrosion, leakage or contamination. Repair any obvious external faults.
With the vehicle in a safe, manufacturer-approved test state, command the pump ON using a scan tool and observe live data: verify command vs. actual status, listen for pump activation, and check for expected voltage and current at the pump connector.
Measure supply voltage at the pump connector while commanded. If voltage is present but pump does not run, isolate electrical issue vs mechanical: measure current draw. High current indicates mechanical seizure; near-zero current indicates open circuit or control fault.
If safe and permitted by manufacturer, disconnect pump (after HV/isolation) and bench-test with a suitable low-voltage supply or follow factory bench procedure. Do not attempt HV component bench tests unless qualified.
Inspect/remove pump and strainer for debris, impeller damage, or seizure. Replace pump if bearings seized or impeller is damaged. Replace damaged hoses, filters, or strainer. Flush and refill coolant per specification and bleed any airlocks.
Inspect and test pump driver circuitry, relay and fuse; if wiring and mechanical pump check OK but driver remains nonfunctional, follow module-level diagnostics or replace faulty driver/module per factory guidance.
After repair, clear codes, re-run the pump/bleed procedure, and test drive or cycle system while monitoring battery temperatures and pump operation to confirm fault does not return.