Limit driving until it's fixed - an underperforming coolant pump can cause the engine to overheat. If you must move the car, watch the temperature gauge closely. P261B means the engine control module (ECM) commanded the electric engine coolant pump but the pump's feedback shows it isn't spinning up as expected - a performance fault. On Toyota hybrids such as the 2014 Avalon, Camry and Prius the ECM runs the electric water pump on a duty-cycle signal to manage warm-up and cooling; when pump speed stays below about 900 rpm while it should be running, the ECM stores P261B.
What P261B means
P261B is a generic powertrain code for the 'B' engine coolant pump control. The ECM varies the electric water pump's speed with a duty-cycle signal based on coolant temperature, engine speed and vehicle speed to speed up warm-up and cut cooling losses. P261B is the performance fault - the pump's reported speed doesn't match what the ECM commanded (below roughly 900 rpm while operating). It is closely related to P261C (control circuit low) and P261D (control circuit high), which describe the same pump seen as a low or high voltage/circuit fault.
Symptoms
- Possible engine overheating or slow warm-up and weak cabin heat
- Check-engine or hybrid system warning depending on model
- P261B stored, often with P261C or P261D
- Cooling fans running more than usual
- Reduced power or a fail-safe mode if the engine actually overheats
Common causes
- Failed electric engine water pump assembly
- Open or short in the pump's control/feedback wiring or connector
- Low system voltage while the pump is operating
- Coolant loss or trapped air affecting pump operation
- Rarely, a faulty ECM driver
Severity & driving advice
Severity: High — A weak coolant pump can let the engine overheat - address it promptly.
Can I drive? Limit driving until it's fixed - an underperforming coolant pump can cause the engine to overheat. If you must move the car, watch the temperature gauge closely.
Diagnostic approach
- Scan and read related codes — Retrieve P261B and any related P261C/P261D, and check coolant level and condition before anything else.
- Inspect the pump wiring and connector — Check the electric water pump connector and harness for open, short, corrosion or damage.
- Verify voltage and grounds — Confirm the system/auxiliary voltage is adequate (roughly 8 V or more) and the grounds are clean.
- Compare commanded vs actual pump operation — With a scan tool, watch the ECM's commanded pump duty against the pump's actual speed while it runs.
- Replace the electric water pump if it underperforms — If wiring and voltage are good but the pump won't reach commanded speed, replace the engine water pump assembly.
- Bleed, clear and confirm — Properly bleed the cooling system, clear the codes, and verify the pump reaches its commanded speed with no overheating.
Estimated repair costs
Typical US repair costs (parts & labour) for the faults behind P261B. These are national-average estimates, not a quote— your actual price varies by region, shop labour rate, and your vehicle’s make, model and year. Figures reviewed 2026.
| Repair | Estimated cost (USD) |
|---|---|
| Diagnosis (scan and inspection) | $90–$150 |
| Wiring/connector repair | $90–$300 |
| Coolant and system bleed | $40–$120 |
| Electric engine water pump assembly | $300–$700 |
Make & model notes
Toyota: Commonly seen on 2014 Toyota hybrids with the 2AR-FXE engine - Avalon Hybrid, Camry Hybrid and related models. The ECM drives the electric engine water pump by duty cycle; P261B is the performance fault when the pump does not reach its commanded speed, and it often appears with P261C or P261D.
FAQ
Is P261B serious?
It can be - a coolant pump that won't reach commanded speed risks engine overheating, so it should be addressed promptly.
What's the difference between P261B, P261C and P261D?
P261B is a performance fault (pump too slow), while P261C and P261D are circuit low and circuit high faults. They usually point at the same pump, wiring or ECM control.
Can I drive with P261B?
Only short distances while watching the temperature gauge. Because overheating is possible, get it repaired as soon as you can.
What is the 'B' engine coolant pump?
It's the electric engine water pump the ECM controls by duty cycle - used especially on hybrids to fine-tune warm-up and cooling.