Lexus AC27A-FXS Engine (2020–present) – Specs, Problems & Compatibility Database

The Lexus AC27A — FXS is a 2,487 cc, inline‑four Atkinson‑cycle petrol engine paired with an electric motor in a series — parallel hybrid system, produced from 2020 onward. It features Toyota’s Dynamic Force architecture with high thermal efficiency (41%), VVT — iE on the intake cam, direct and port fuel injection (D — 4S), and cooled exhaust gas recirculation (EGR). The combined system output is 164 kW (223 PS), with electric — only operation up to 140 km/h under light load.

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Lexus Engine
Compliance Note:

All production years (2020–present) meet Euro 6d emissions standards .

Lexus AC27A-FXS Technical Specifications

The Lexus AC27A-FXS is a 2,487 cc inline‑four Atkinson‑cycle hybrid petrol engine engineered for premium compact SUVs (2020–present). It combines D-4S dual injection with VVT-iE variable valve timing to deliver smooth electric-assisted acceleration and low urban emissions. Designed to meet Euro 6d standards, it balances refinement, efficiency, and hybrid drivability.

ParameterValueSource
Displacement
2,487 cc
Fuel type
Petrol (RON 95 min)
Configuration
Inline‑4, DOHC, 16‑valve, Atkinson cycle
Aspiration
Naturally aspirated
Bore × stroke
87.5 mm × 103.4 mm
Power output
118 kW (160 PS) petrol + 46 kW (62 PS) electric = 164 kW (223 PS) combined
Torque
207 Nm (petrol) + 207 Nm (electric) = 221 Nm system torque
Fuel system
D-4S (direct + port injection)
Emissions standard
Euro 6d
Compression ratio
14.0:1
Cooling system
Water‑cooled (dual circuit: engine + inverter)
Turbocharger
None
Timing system
Chain-driven DOHC
Oil type
Toyota Genuine Motor Oil 0W‑20 (ILSAC GF-6 / API SP)
Dry weight
138 kg (engine only)

Lexus AC27A-FXS Compatible Models

The Lexus AC27A-FXS was used exclusively in Lexus's AZ20 platform with transverse mounting and shared with Toyota for the Harrier Hybrid in Japan and select Asian markets. This engine received platform-specific adaptations—reinforced subframes for NVH control in the NX 350h and revised inverter mounting in the Harrier—with no facelift revisions affecting core compatibility as of 2025. All adaptations are documented in OEM technical bulletins.

Make:
Lexus
Years:
2020–present
Models:
NX 350h (AZ20)
Variants:
NX 350h
View Source
Lexus EPC #LX‑AZ20‑2023
Make:
Toyota
Years:
2020–present
Models:
Harrier Hybrid (XU80)
Variants:
2.5 Hybrid
View Source
Toyota EPC #TJ‑XU80‑2022

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Common Reliability Issues - LEXUS AC27A-FXS Compatible Models

Field reports and technical service bulletins highlight component wear patterns under high-load operation. Adherence to manufacturer service intervals and approved fluid specifications is critical for long-term reliability.

Inverter coolant pump seal failure
Symptoms: Green coolant residue near inverter, hybrid system warning light, reduced EV mode availability.
Cause: Early-design seals in the electric coolant pump degrade under thermal cycling, leading to slow leaks.
Fix: Replace pump assembly with updated part (P/N 16400‑52090) per Toyota Service Campaign TSC‑2022‑04.
Hybrid transaxle oil degradation
Symptoms: Whining noise under acceleration, reduced regenerative braking efficiency, MG1/MG2 temperature warnings.
Cause: Extended drain intervals or incorrect fluid (non-WS spec) cause viscosity breakdown in the transaxle.
Fix: Drain and refill with Toyota Genuine ATF WS fluid every 100,000 km or 8 years per TIS guidance.
Intake manifold carbon buildup
Symptoms: Minor hesitation on cold start, slight increase in fuel consumption, rough idle after long idle.
Cause: Port injection reduces but doesn't eliminate carbon; EGR deposits accumulate over time.
Fix: Clean intake runners and EGR valve per OEM procedure; no disassembly needed on AC27A due to port+direct injection.
12V auxiliary battery premature failure
Symptoms: ‘Check Hybrid System’ on startup, slow cranking (for A/C compressor), infotainment reset.
Cause: AGM battery stressed by frequent DC-DC converter cycling in stop-start urban driving.
Fix: Replace with OEM-spec AGM battery (Toyota P/N 28800‑52020); verify DC-DC output voltage during replacement.
Research Basis

Analysis derived from manufacturer technical service bulletins and industry workshop records. Repair procedures should follow manufacturer guidelines.

LEXUS AC27A-FXS FAQ Common Questions Answered

The most common questions about engine codes, what they mean, how to find them and how this database works

Yes. The AC27A-FXS is based on Toyota’s proven Dynamic Force hybrid architecture with strong long-term reliability. Early 2020–2021 models had a minor inverter pump issue (addressed under service campaign), but otherwise the engine shows excellent durability. Regular 12V battery checks and correct ATF WS fluid changes ensure hybrid system longevity.

The main documented issue is inverter coolant pump seal wear in early builds (TSC‑2022‑04). Other minor concerns include 12V AGM battery fatigue in city driving and slow transaxle fluid degradation. Carbon buildup is minimal due to D-4S injection. All are manageable with scheduled maintenance.

The AC27A-FXS is used exclusively in the Lexus NX 350h (AZ20 series, 2020–present). It is also found in the mechanically identical Toyota Harrier Hybrid (XU80) in Japan and Asia. No other Lexus or Toyota models currently use this specific hybrid variant.

No. The AC27A-FXS hybrid system is tightly integrated with the transaxle and ECU; no safe or OEM-supported tuning paths exist. Power output is managed by the hybrid control unit, and modifications risk inverter or battery damage. Toyota does not endorse performance remapping for this powertrain.

Excellent. The NX 350h achieves ~5.3 L/100km combined (WLTP), or ~53 mpg UK. Real-world mixed driving typically yields 45–55 mpg (UK). Electric-only mode covers short urban trips, while highway cruising uses the efficient Atkinson cycle. Economy depends heavily on driving style and battery state.

Yes. Like all modern Toyota/Lexus engines, the AC27A-FXS is an interference design. However, it uses a maintenance-free timing chain with no known wear issues. Chain failure is extremely unlikely under normal conditions, but catastrophic if it occurs.

Toyota specifies 0W‑20 synthetic oil meeting ILSAC GF-6 and API SP standards (e.g., Toyota Genuine Motor Oil). This low-viscosity oil is critical for VVT-iE solenoid response and fuel economy. Change intervals are 16,000 km or 12 months under normal conditions.

Research Resources

Comprehensive technical documentation and regulatory references

Platform Overview

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Primary Sources

EUR-Lex

EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).

GOV.UK: Vehicle Approval & V5C

UK vehicle approval processes, import rules, and MoT guidance.

DVLA: Engine Changes & MoT

Official guidance on engine swaps and inspection implications.

Vehicle Certification Agency (VCA)

UK type-approval authority for automotive products.

Regulatory Context

Regulation (EC) No 715/2007

Euro emissions framework for vehicle type approval.

Commission Regulation (EU) 2017/1151

WLTP and RDE testing procedures for emissions certification.

GOV.UK: Vehicle Approval

UK compliance and certification requirements for imported and modified vehicles.

VCA Certification Portal

Type-approval guidance and documentation.

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