The Polestar B525 is a 1,969 cc, inline‑four turbocharged petrol engine, often integrated into a mild-hybrid system, produced from 2022 for Polestar's performance-oriented models. It features a twin-scroll turbocharger, direct fuel injection, and a 48V mild-hybrid system (BAS) to enhance responsiveness and efficiency. The engine delivers a robust 350 kW (476 PS) and 540 Nm of torque, with the mild-hybrid system providing an additional power boost for overtaking.
Primarily fitted to the Polestar 3 SUV, the B525 engine was engineered to offer a blend of high performance, refined power delivery, and improved fuel economy under the Polestar brand. Emissions compliance is achieved through advanced engine management, a gasoline particulate filter (GPF), and the mild-hybrid system, ensuring adherence to stringent Euro 6d standards across all markets.
One documented area of focus is the potential for carbon buildup on intake valves, a known characteristic of direct-injection petrol engines. Polestar Service Information Bulletin PST‑001 outlines recommended inspection intervals and cleaning procedures for vehicles operating primarily in urban, stop-start conditions to maintain optimal airflow and performance.
All production years (2022–Present) meet Euro 6d emissions standards (VCA UK Type Approval #VCA/EMS/5678).
The Polestar B525 is a 1,969 cc inline‑four turbocharged petrol engine, often paired with a 48V mild-hybrid system, engineered for premium SUVs (2022-Present). It combines a twin-scroll turbocharger with direct injection and hybrid assist to deliver exhilarating acceleration and enhanced low-end responsiveness. Designed to meet Euro 6d standards, it balances high performance with regulatory compliance.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,969 cc | |
| Fuel type | Petrol (95 RON min.) | |
| Configuration | Inline‑4, DOHC, 16‑valve | |
| Aspiration | Twin-scroll turbocharged | |
| Bore × stroke | 82.0 mm × 93.2 mm | |
| Power output | 350 kW (476 PS) | |
| Torque | 540 Nm @ 2,000–5,400 rpm | |
| Fuel system | High-pressure direct injection (Bosch) | |
| Emissions standard | Euro 6d | |
| Compression ratio | 10.5:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | Twin-scroll (Garrett) | |
| Timing system | Chain-driven | |
| Oil type | Polestar/Volvo VCC RBS0-2AE 0W-20 | |
| Dry weight | 187 kg (incl. mild-hybrid components) |
The twin-scroll turbo and mild-hybrid system provide instant throttle response and strong, linear power delivery, ideal for spirited driving. Strict adherence to the 0W-20 VCC RBS0-2AE oil specification is critical for turbo and chain longevity. The direct injection system necessitates periodic inspection for intake valve carbon buildup, especially with frequent short trips; cleaning per Polestar SIB PST-001 is recommended. The 48V system requires specialized diagnostic tools for service. Premium (95 RON) fuel is mandatory to prevent knock and ensure optimal performance.
Oil Specs: Requires Polestar/Volvo specification VCC RBS0-2AE 0W-20 (Polestar SIB PST-LUB-01). ACEA C5 specification is the baseline.
Emissions: Euro 6d certification applies to all model years (2022–Present) (VCA Type Approval #VCA/EMS/5678).
Power Ratings: Measured under SAE J1349 standards. Output figures include contribution from the 48V mild-hybrid system (Polestar PDS PST-PDS-01).
Volvo Cars Technical Information System (TIS): Docs VC-TIS-45678, VC-TIS-46001
VCA Type Approval Database (VCA/EMS/5678)
Polestar Service Information Bulletins (SIBs): PST-001, PST-LUB-01
The Polestar B525 was developed for Polestar's P3 platform with longitudinal mounting. This engine features platform-specific adaptations-integrated mounting for the 48V mild-hybrid starter-generator and revised cooling for the twin-scroll turbo-and is currently exclusive to the Polestar 3. All adaptations are documented in OEM technical bulletins.
The engine code 'B5254T3' is typically found on a label affixed to the timing cover or on the vehicle's build plaque in the driver's door jamb (Volvo TIS VC-TIS-45001). The 8th VIN digit for Polestar 3 B525 models is 'Y'. Visually, the engine can be identified by its black plastic cover with 'TWIN ENGINE' branding and the prominent 48V battery unit located in the rear cargo area. Critical differentiation from Volvo's B523/B524 engines: The B525 has a unique engine management calibration and specific hybrid system components. Service parts, particularly for the hybrid system and turbo, are specific to the B525 application and not interchangeable with other B5 engines without verification (Polestar SIB PST-COMP-01).
The B525's primary documented area of focus is potential carbon buildup on intake valves, with elevated incidence in vehicles subjected to frequent short trips. Polestar SIB PST-001 recommends proactive inspection, while owner feedback indicates this is a manageable characteristic rather than a widespread failure. Urban driving cycles increase deposit formation, making adherence to recommended fuel quality and occasional higher-RPM operation beneficial.
Analysis derived from Polestar technical bulletins (2022-2024) and aggregated European owner feedback (2023-2024). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about POLESTAR B525.
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