P261B on Toyota: How to Diagnose & Fix
Coolant Pump "B" Control Circuit Range/Performance
1 Toyota model · 1 documented issue · 1 critical · $250-$800 repair
P261B on Toyota by model: symptoms, diagnosis and fix
Unlike a belt-driven pump, the 2ZR-FXE engine coolant pump is a brushless electric unit commanded by duty cycle from the ECM. The internal motor/controller degrades and the pump slows or stops, so coolant stops circulating through the engine. The ECM detects the speed feedback falling below threshold and sets P261B (or P261C), lights the check engine and hybrid warning lights, and will shut the gas engine down to protect it, leaving the car crawling on battery only. Toyota addressed it with T-SB-0143-10 and a revised pump design; it is one of the most-reported repairs on third-gen Prius, Prius v, Prius c and Lexus CT200h.
Common Symptoms
- Check engine light with hybrid system warning
- Engine temperature climbing, overheat message
- No coolant movement visible in the reservoir with engine running
- Gas engine shuts down or car enters limp mode
- Heater blows cold
How to Fix
Confirm with the code plus a visual check of coolant flow in the reservoir with the engine running. Replace the electric engine water pump with the updated Aisin/Toyota unit (do not reuse the old O-ring), refill and run the Techstream/manual air-bleed procedure - trapped air in this system will cause repeat overheat codes and can mimic a second pump failure. It is a 1-2 hour job accessible from the passenger side of the engine. Cheap no-name aftermarket pumps are a common repeat-failure complaint.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Aisin WPT-190 electric engine water pump
replace an engine coolant pump proven slow, electrically faulty or non-operational after circuit diagnosis Fitment/availability: 2010-2015 Prius 1.8L 2ZR-FXE; Aisin also catalogs the branch for 2012-2015 Prius Plug-in and 2012-2018 Prius…
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Sources for this issue (3)
P261B code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P261B mean on a Toyota?
P261B stands for "Coolant Pump "B" Control Circuit Range/Performance." This code sets when the engine control module commands the electric (auxiliary) coolant pump "B" but the circuit's behavior or feedback does not match what is expected for the commanded state. Coolant pump "B" is typically an electric auxiliary pump that helps circulate coolant for engine, turbo, hybrid, or A/C-related cooling. A range/performance fault means the pump or its control circuit is responding sluggishly or incorrectly, which risks overheating if coolant is not moving properly. On Toyota it is documented across 1 model: Prius.
What are the most common causes of P261B?
The most common causes of P261B are: Failing or seized electric auxiliary coolant pump, Wiring or connector fault in the pump control circuit, Corroded or loose pump connector, Low coolant level or air in the system, Faulty pump relay or power supply, Control module (ECM) driver fault (less common). The specific cause varies by vehicle.
How much does it cost to fix P261B on a Toyota?
Published repair estimates on Toyota range from $250 to $800 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P261B on a different make?
View P261B across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.