P26B4 on MINI: How to Diagnose & Fix
Charge Air Cooler Coolant Pump Performance
1 MINI model · 1 documented issue · 1 critical · $500-$1,200 repair
P26B4 on MINI by model: symptoms, diagnosis and fix
The electric water pump on the N18 and B48 engines is a known failure point across the BMW/MINI platform. The pump motor or impeller fails, causing loss of coolant circulation and rapid overheating. Unlike mechanical water pumps that give gradual warning signs, the electric pump can fail suddenly with no prior symptoms. The GP engines run hotter than standard MINI models, putting additional stress on the pump. Failure typically occurs between 50,000-100,000 miles.
Common Symptoms
- Engine temperature rising rapidly to red zone
- Coolant temperature warning on dashboard
- No heat from heater (coolant not circulating)
- Coolant boiling over
- Electric pump not audible when ignition is on (normally faint hum)
- Steam from engine bay
How to Fix
Replace the electric water pump and thermostat together ($300-$600 for parts, $200-$400 labor). The thermostat is also electronically controlled and commonly fails alongside the pump. Use OEM or Pierburg (OEM supplier) replacement parts. Flush the cooling system with fresh BMW coolant during the repair. As preventive maintenance, replace the water pump at 80,000 miles even if it is still working — the cost of a planned replacement is far less than an engine overheated by a failed pump. Always carry coolant and monitor the temperature gauge closely on older GP models.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Saleri MINI N18 water pump 11517648827OEMSaleri PA1425 / MINI 11517648827
Confirm GP2 VIN and the main-pump failure
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Owner tips & cautions
- WarningIf the temperature gauge climbs past the middle mark, STOP DRIVING IMMEDIATELY. The electric water pump gives zero warning before complete failure. Overheating for even 2 minutes can warp the cylinder head.
- TipReplace the water pump and thermostat together at 80,000 miles as preventive maintenance. The parts are $400-$500 and the labor overlaps. Cheap insurance against a catastrophic overheat.
Sources for this issue (1)
P26B4 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 P26B4 mean on a MINI?
P26B4 stands for "Charge Air Cooler Coolant Pump Performance." P26B4 is a powertrain code relating to the charge air cooler (intercooler) coolant pump performance on a liquid-cooled intercooler system, where an electric pump circulates coolant to cool the pressurized intake air from the turbocharger. The computer commands the pump and monitors flow, speed, or current, and sets this code when the pump's performance is outside the expected range. This can lead to higher intake air temperatures, reduced boost or power, and possible knock protection. It points to the charge-air-cooler coolant pump or its loop rather than the main engine cooling system. On MINI it is documented across 1 model: GP.
What are the most common causes of P26B4?
The most common causes of P26B4 are: Failed or weak charge air cooler coolant pump, Low coolant or air pocket in the intercooler loop, Coolant leak in the charge air cooler circuit, Clogged or restricted intercooler coolant passages, Wiring, connector, fuse, or relay fault at the pump, Faulty coolant temperature or flow sensor in the loop, PWM control or driver fault in the controlling module. The specific cause varies by vehicle.
How much does it cost to fix P26B4 on a MINI?
Published repair estimates on MINI range from $500 to $1,200 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 P26B4 on a different make?
View P26B4 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.