| Home / Car Engines / Toyota Engines / Toyota A25A-FKS |
Toyota A25A-FKS Specifications
| Engine Model: Toyota A25A-FKS |
| Engine Type: 4-cycle inline 4-cylinder DOHC 16-valve VVT-i liquid-cooled gasoline |
| Total Displacement: 151.8 cu.in (2.49 L) |
| Rated Engine Power: 202-208 Hp (151-155 kW) at 6600 rpm |
| Fuel System Type: Toyota D-4S direct injection |
____________________________________________________________________________________
- Toyota 2F Engine Specifications
- Toyota 7M-GE Engine Specifications
- Toyota V35A-FTS Engine Specifications
| General Technical Data |
The Toyota A25A-FKS engine is a 2.5-liter inline four-cylinder gasoline powerplant belonging to the Dynamic Force engine family, introduced in 2017 as part of Toyota’s TNGA (Toyota New Global Architecture) strategy. It replaced the older 2AR-FE engine and marked a major step forward in efficiency, emissions control, and performance.
The A25A-FKS employs advanced technologies such
as a long-stroke design, high compression ratio, D-4S dual injection
(direct and port), VVT-iE (Variable Valve Timing – intelligent Electric)
on the intake side, and VVT-i on the exhaust. It was developed for
medium and large front-wheel-drive and all-wheel-drive vehicles,
providing a balance between performance, fuel efficiency, and
environmental compliance.
The engine first appeared in the 2018 Toyota Camry and later became the
mainstay 2.5-liter unit in many Toyota and Lexus models. It features a
thermally efficient Atkinson-cycle operation under part-load conditions
and Otto-cycle under full load. The A25A-FKS achieves up to 41% thermal
efficiency in the standard version, rising slightly in the updated Euro
6 (2020-on) variant due to refinements in fuel injection mapping,
combustion chamber geometry, and exhaust gas recirculation (EGR)
control.
These improvements were made to meet the
stricter Euro 6d and LEV3 emissions standards while maintaining
durability and smooth operation. Known for its refinement and torque
spread, the A25A-FKS combines modern lightweight design with exceptional
longevity when maintained according to Toyota specifications.
The A25A-FKS has a total displacement of 2,487 cc (2.49 liters or 151.8
cubic inches). Bore and stroke dimensions are 87.5 mm (3.44 inches) and
103.4 mm (4.07 inches) respectively, giving it a long-stroke
configuration that promotes strong low- and mid-range torque. The
compression ratio is 13.0:1 in the standard version and slightly
increased to 13.3:1 in later Euro 6 versions due to optimized piston
crown design and combustion chamber shape.
The cylinder block is cast aluminum with
cast-iron cylinder liners and an open-deck structure with integrated
coolant passages for efficient heat dissipation. The crankshaft is
forged steel with five main bearings, and balance shafts are used to
reduce secondary vibration.
The cylinder head is made of aluminum alloy and houses dual overhead
camshafts operating four valves per cylinder via roller rocker arms and
hydraulic lash adjusters. The valve diameters are approximately 35.8 mm
(1.41 in) intake and 29.0 mm (1.14 in) exhaust. The A25A-FKS uses
Toyota’s advanced D-4S fuel injection system, which combines direct and
port injection to optimize combustion under varying loads. The intake
camshaft features VVT-iE – an electric actuator for precise and fast
control of valve timing, even at cold starts – while the exhaust
camshaft uses a hydraulically actuated VVT-i system.
Maximum power output for the standard A25A-FKS is approximately 152 kW
(203 horsepower, 206 PS, or 200 bhp) at 6,600 rpm, while torque peaks at
250 Nm (184 lb-ft) at 5,000 rpm. The Euro 6d version produces around
151–155 kW (202–208 hp) and 243–252 Nm (179–186 lb-ft), depending on
application and calibration. The engine redline is approximately 6,800
rpm, with idle speed at 650 ± 50 rpm. The firing order is 1–3–4–2, and
crankshaft rotation is clockwise when viewed from the flywheel end.
The aluminum pistons have low-friction coatings and cooling oil jets
beneath each piston to maintain thermal stability. Connecting rods are
forged steel and lightweight. The camshafts are chain-driven by a
single-row roller chain with a hydraulic tensioner. The valve timing
system allows wide phase ranges: about 70° crank angle on the intake and
50° on the exhaust. The combustion chamber is compact, and the intake
ports are designed to generate high tumble flow, enhancing air-fuel
mixing efficiency. These design choices contribute to Toyota’s
class-leading thermal efficiency.
| Fuel System |
The D-4S fuel injection system is the highlight of the A25A-FKS. It uses
both port injectors and direct injectors, coordinated by the engine
control unit (ECU) to achieve optimal combustion for all conditions. At
low and medium load, the port injectors operate predominantly to
minimize particulate emissions and intake valve deposits, while at
higher load and speed, direct injectors are activated for precise
high-pressure delivery. The high-pressure fuel pump, driven by the
intake camshaft, delivers up to 20 MPa (2,900 psi) fuel pressure to the
direct injectors. The low-pressure system supplies fuel to both the
high-pressure pump and port injectors via an electric in-tank pump
operating at around 400 kPa (58 psi).
The fuel used is unleaded gasoline with a minimum of 95 RON (91 AKI).
The D-4S system ensures excellent atomization and mixture control,
reducing knock sensitivity even with the high compression ratio. The
injectors are multi-hole type, optimized for spray angle and droplet
size. The system employs a returnless fuel rail to reduce vapor
emissions. The fuel filter is integrated with the fuel pump assembly and
is typically maintenance-free throughout the vehicle’s life. Fuel
pressure sensors and temperature sensors provide feedback to the ECU,
ensuring stable operation across wide ambient and altitude ranges.
| Lubrication System |
The lubrication system is a fully pressurized, wet-sump type using a variable-displacement trochoid oil pump driven by the crankshaft through a chain. The oil pressure is electronically controlled according to engine load and speed, reducing parasitic losses. Typical oil pressure values are around 350 kPa (51 psi) at 3,000 rpm and about 100 kPa (15 psi) at idle. The oil capacity with filter is 4.5 liters (4.8 US quarts, 3.9 Imperial quarts).
Recommended oil viscosity is SAE 0W-16 or 0W-20 meeting API SN or ILSAC GF-6 standards. Toyota specifies synthetic oil for all operating conditions. The engine incorporates piston cooling jets, an oil cooler integrated into the filter housing, and an electronically controlled PCV (positive crankcase ventilation) system to manage blow-by gases and crankcase pressure. The filter is a replaceable cartridge type with anti-drainback and bypass valves.
| Cooling System |
The cooling system is a pressurized, liquid-cooled, cross-flow design with an electric water pump in the Euro 6 version and a belt-driven pump in earlier models. Coolant circulation covers the cylinder block, head, throttle body, and EGR cooler. The thermostat opens at approximately 82°C (180°F) and is fully open near 95°C (203°F). Total coolant capacity is about 6.2 liters (6.5 US quarts, 5.4 Imperial quarts). The system includes a high-efficiency aluminum radiator, electric cooling fans, and a coolant reservoir.
In the later Euro 6 version, an electric coolant control valve and electronically managed pump provide variable coolant flow to accelerate warm-up and reduce parasitic losses. Recommended coolant is Toyota Super Long-Life Coolant (SLLC), a pink ethylene glycol-based antifreeze with a service life of up to 160,000 km (100,000 miles) or 5 years for the first interval and 80,000 km (50,000 miles) thereafter.
| Intake and Exhaust Systems |
The intake system employs a variable-length intake manifold with tumble control valves to optimize airflow at different engine speeds. The air cleaner element is a dry paper type, replaced every 30,000 km (18,600 miles). The throttle body is electronically controlled (ETCS-i) and features a 60-mm (2.36-inch) bore. The exhaust manifold is integrated into the cylinder head for improved heat management and faster catalyst warm-up.
The exhaust system includes a close-coupled three-way catalytic converter, downstream catalytic converter, and oxygen sensors for feedback control. The Euro 6 variant features an additional particulate filter (GPF) to comply with EU emission standards. The EGR system recirculates cooled exhaust gases under part-load conditions, improving efficiency and reducing NOx formation.
| Ignition and Electrical System |
The ignition system is a coil-on-plug type, with iridium-tipped spark plugs (Denso FK20HR11 or equivalent) gapped at 1.0 mm (0.039 in). Each plug has its own ignition coil controlled by the ECU, which also governs injection timing, valve phasing, throttle operation, and fuel-air mixture. The alternator output is rated between 130 and 150 amperes depending on application.
The starting motor is reduction-gear type rated at 1.6 kW. The battery voltage is 12 V nominal, with standard capacity between 60 and 70 Ah. The Euro 6 version integrates energy management for idle stop/start systems, utilizing an enhanced alternator and battery monitoring system.
| Valve Timing and Drive Mechanism |
A single roller timing chain drives both camshafts through an intermediate gear arrangement. The chain tension is hydraulically maintained, and service inspection for wear is recommended at 200,000 km (125,000 miles). The VVT-iE actuator on the intake camshaft operates via an electric motor with reduction gears, allowing rapid and precise adjustment even at low oil pressure or cold start. The exhaust camshaft uses oil pressure control through a hydraulic actuator. This configuration enables fast switching between Atkinson and Otto cycles by adjusting intake valve closing timing, maximizing efficiency without sacrificing power.
| Dimensions and Weight |
The overall dimensions of the A25A-FKS engine are approximately 610 mm (24.0 inches) in length, 650 mm (25.6 inches) in width, and 685 mm (27.0 inches) in height. The dry weight is around 150 kg (331 lbs) for the standard version and 153 kg (337 lbs) for the Euro 6 update due to added emission hardware. The compact dimensions and lightweight aluminum structure make it well-suited for transverse installation in FWD and AWD configurations. The engine uses three-point mounts with hydraulic dampers for reduced NVH levels.
| Maintenance Data |
Toyota recommends engine oil and filter replacement every 10,000 km (6,000 miles) or 12 months, whichever comes first. Under severe conditions or frequent short trips, intervals should be shortened to 5,000 km (3,000 miles). Spark plugs should be replaced every 120,000 km (75,000 miles). The air filter should be replaced every 30,000 km (18,600 miles) and inspected every 15,000 km (9,300 miles). Coolant replacement intervals follow the Super Long-Life Coolant schedule.
The serpentine accessory belt should be inspected every 60,000 km
(37,000 miles) and replaced if cracked or worn. The timing chain is
designed for the life of the engine but should be inspected for
elongation beyond 0.5% at high mileage. The valve clearance is
self-adjusting via hydraulic lifters and requires no periodic
adjustment. The PCV valve should be inspected every 80,000 km (50,000
miles).
Compression pressure in each cylinder should measure approximately 1,400
kPa (203 psi) at 300 rpm, with a minimum of 1,100 kPa (160 psi) and
maximum difference between cylinders of 100 kPa (15 psi). Idle speed is
650 ± 50 rpm. Standard fuel pressure is 400 kPa (58 psi) low-pressure
and 20 MPa (2,900 psi) high-pressure side.
| Tightening Torques |
Cylinder head bolts: initial 30 Nm (22 lb-ft), second stage 90 degrees,
final stage 90 degrees.
Main bearing cap bolts: 60 Nm (44 lb-ft) plus 90 degrees.
Connecting rod bolts: 40 Nm (30 lb-ft) plus 90 degrees.
Camshaft bearing cap bolts: 10 Nm (7 lb-ft).
Crankshaft pulley bolt: 180 Nm (133 lb-ft).
Flywheel bolts: 85 Nm (63 lb-ft).
Spark plugs: 25 Nm (18 lb-ft).
Oil drain plug: 40 Nm (30 lb-ft).
Exhaust manifold nuts: 35 Nm (26 lb-ft).
Intake manifold bolts: 25 Nm (18 lb-ft).
Engine mount bolts: 60 Nm (44 lb-ft).
Valve cover bolts: 9 Nm (7 lb-ft).
| Vehicle Applications |
The Toyota A25A-FKS engine powers a wide
range of Toyota and Lexus models, including:
– Toyota Camry (XV70, 2018–present)
– Toyota RAV4 (XA50, 2018–present)
– Toyota Highlander (XU70, 2019–present)
– Toyota Avalon (XX50, 2018–present)
– Toyota Harrier and Venza (XU80, 2020–present)
– Lexus ES250 / ES300h (with hybrid system variant A25A-FXS)
– Toyota Kluger and Crown Cross (regional markets)
The Euro 6 A25A-FKS variant, introduced around 2020, includes upgraded
catalytic converters, a gasoline particulate filter (GPF), and revised
ECU calibration to meet Euro 6d and LEV3 emission requirements. Power
and torque remained nearly identical, but transient response and
cold-start emissions improved significantly.
The combination of D-4S injection, high compression, and advanced timing control allows excellent drivability with minimal fuel consumption, typically around 6.0–7.0 liters per 100 km (40–47 mpg US) in mid-size sedans. The engine’s design ensures long service life, low oil consumption, and minimal maintenance when high-quality lubricants and fuels are used.
____________________________________________________________________________________
| Car Engines Technical Specifications |
| Small Engines Technical Specifications |
| Industrial Engines Technical Specifications |
| Outboard Engines Technical Specifications |