P261B on Mercedes-Benz
Coolant Pump "B" Control Circuit Range/Performance
P261B on Mercedes-Benz vehicles indicates coolant pump "b" control circuit range/performance. Au7o has documented this code across 1 Mercedes-Benz model — most commonly on GLE. 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. Typical repair costs on Mercedes-Benz range from $600 to $2,200, depending on the specific model and root cause.
Common Causes of P261B
- •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)
P261B on Mercedes-Benz by Model
Mercedes-Benz GLE(1 issue)
- M256 Inline-6 Oil Filter Housing / Oil Cooler and Electric Coolant Pump Leaks2020-2025
The 3.0L M256 inline-six (GLE 450, AMG GLE 53 on the W167) is prone to oil leaks from the oil filter housing/adapter assembly, which integrates the engine oil cooler with coolant passages, making leaks both oil and coolant related. The M256 also relies on an electric coolant pump and an auxiliary electric water pump that can fail, producing erratic cooling behavior and overheating warnings. Because oil and coolant circuits share the adapter, an internal cooler leak can let coolant migrate into the oil and quickly damage the engine. Owners also report cold-start timing-chain rattle and oil consumption past ~60k miles on this engine.
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What does P261B mean on Mercedes-Benz?▼
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 Mercedes-Benz specifically, this code is documented across 1 model.
What causes P261B on Mercedes-Benz vehicles?▼
Common causes on Mercedes-Benz: 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. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P261B on a Mercedes-Benz?▼
Repair costs on Mercedes-Benz range from $600 to $2,200, depending on the specific model and root cause.
Which Mercedes-Benz models have P261B documented?▼
Au7o has documented P261B on 1 Mercedes-Benz model: GLE.