P261B on Cadillac: How to Diagnose & Fix
Coolant Pump "B" Control Circuit Range/Performance
1 Cadillac model · 1 documented issue
P261B on Cadillac by model: symptoms, diagnosis and fix
GM issued a Customer Satisfaction Program bulletin (December 2020) stating the printed circuit board inside the electric water pump on affected CT4/CT5 vehicles may have been manufactured incorrectly, potentially causing a water pump failure; when this occurs the vehicle displays warnings as coolant temperatures rise, the oil pressure gauge falsely indicates high oil pressure, a reduced power/torque message appears, and if ignored the AC is disabled, the driver is told to idle, and the engine can then be shut down. The 2.0L LSY turbo-four (base engine in the CT5) is one of the engines susceptible to this water pump failure (the other being the 2.7L L3B, which is not used in the CT5).
Common Symptoms
- High coolant temperature warning
- Oil pressure gauge falsely reading high
- 'Reduced engine power' message
- AC compressor cut out
- Chime and message telling the driver to idle; engine may shut down
- No coolant flow at idle
How to Fix
Dealers replace the entire electric water pump assembly; GM allows 2.1 labor hours on the CT4/CT5, and the work was performed at no cost to the owner under Customer Satisfaction Program N202320510. The program coverage window ran through December 31, 2022, so out-of-warranty owners now face out-of-pocket cost. Independent shop cost for the electric pump assembly typically runs $700–$1,400 parts plus labor. Diagnose by scanning for coolant temp DTCs (the program bulletin names DTC P2B85) and observing the false-high oil pressure indication, which is a hallmark of this specific failure mode.
Sources for this issue (1)
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 Cadillac?
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 Cadillac it is documented across 1 model: CT5.
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 Cadillac?
Repair costs vary widely with the root cause and Cadillac model; each issue on this page carries its own estimate where one is published.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.