1AZ-FE Engine

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AZ series was introduced since 2000 – to gradually supplant the legendary S series, and for ten years remained the main mid-size engine of the company. Installed in many initially FF C/D/E-class cars, vans, light- and medium-SUVs.

The 1AZ-FE engine can be seen as a simplified version of 2AZ-FE.

  • There is no balancing mechanism.
  • No oil nozzles in the block.
  • Pistons have a larger skirt.

– For some regions, specific modifications were produced – for leaded gasoline, without VVT, without the converter and relative components.

1AZ-FSE (2.0 D-4) and 2AZ-FSE (2.4 D-4)

1AZ-FSE, 2AZ-FSE – transverse, with direct injection, for initially FF cars, vans, and SUVs. Installed in: Allion/Premio 240, Avensis 220..250, Caldina 240, Gaia, Isis, Nadia, Noah/Voxy 60, Opa, RAV4 20, Vista 50, Wish 10.
By 2009 replaced by ZR engines with traditional multipoint injection (and Valvematic system).

There are some differences in the mechanical part of D-4 engines.

  • The higher the compression ratio.
  • The fuel injectors are mounted in the cylinder head.
  • A high-pressure fuel pump is driven by an additional cam on the inlet camshaft.
  • Variable valve timing range 43°.

– The pistons has the specify shape which help to lead the fuel spray to the area of the spark plug. The top ring groove has anti-wear alumite coating.

– Some models was equipped with oil cooler.

1 – water pump, 2 – bypass, 3 – to heater, 4 – to radiator, 5 – from ATF heater, 6 – to ATF heater, 7 – thermostat, 8 – drain, 9 – oil cooler, 10 – from radiator.

– Differences of version for Japanese domestic market (type’2004): a compression ratio 10.5 instead of 9.8, three-layer cylinder head gasket instead of a two-layer, other shape of the combustion chamber, additional channels for coolant between the cylinders, the other valve timing, intake valve lift 9.4 instead of 8.2 mm, exhaust – 8.0 instead of 8.6 mm, reduced by 1.1 mm piston height.

1AZ specs

Manufacturer Kamigo Plant
Shimoyama Plant
Also called Toyota 1AZ
Production 2000-present
Cylinder block alloy Aluminum
Configuration Straight-4
Valvetrain DOHC
4 valves per cylinder
Piston stroke, mm (inch) 86 (3.39)
Cylinder bore, mm (inch) 86 (3.39)
Compression ratio 9.6
Displacement 1998 cc (121.9 cu in)
Power output 108 kW (145 HP) at 6,000 rpm
110 kW (150 HP) at 5,700 rpm
111 kW (150 HP) at 6,000 rpm
112 kW (152 HP) at 6,000 rpm
Torque output 190 Nm (140 lb·ft) at 4,000 rpm
193 Nm (142 lb·ft) at 4,000 rpm
193 Nm (142 lb·ft) at 4,000 rpm
200 Nm (148 lb·ft) at 4,000 rpm
HP per liter 72.6
Fuel type Gasoline
Weight, kg (lbs) 131 (290)
Fuel consumption, L/100 km (mpg)
for RAV4 XA20
11.4 (20)
7.3 (32)
9.8 (24)
Turbocharger  Naturally aspirated
Oil consumption, L/1000 km
(qt. per miles)
up to 1.0
(1 qt. per 750 miles)
Recommended engine oil 0W-20
Engine oil capacity, L (qt.) 4.2 (4.4)
Oil change interval, km (miles) 5,000-10,000
Normal engine operating temperature, °C (F)
Engine lifespan, km (miles)
-Official information

300,000+ (180,000)
Tuning, HP
-Max HP
-No life span loss

The engine is installed in:

  • 2006–2009 Toyota Camry (Aurion version)
  • 2001–2003 Toyota RAV4
  • 2003-2006 Toyota RAV4 Euro
  • 2001–2009 Toyota Ipsum
  • Toyota Avensis
  • Toyota Avensis Verso
  • Toyota Noah/Voxy
  • Toyota RAV4
  • Toyota Gaia
  • Toyota Isis
  • Toyota Ipsum
  • Toyota Caldina
  • Toyota Wish
  • Toyota Allion
  • Toyota Premio
  • Toyota Opa

ETCS (electronic throttle control)

Driven by motor with control unit commands. When starting the throttle is slightly opened to allow additional air intake, and then the opening angle decreases depending on the coolant temperature. At the homogeneous mode idling speed is adjusted by throttle moving, at LeanBurn mode – by fuel supply volume correction with constant throttle opening. In addition, ETCS performs traction control (TRC) function and some stabilization system (VSC) functions.

Driven by motor with control unit commands. When starting the throttle is slightly opened to allow additional air intake, and then the opening angle decreases depending on the coolant temperature. At the homogeneous mode idling speed is adjusted by throttle moving, at LeanBurn mode – by fuel supply volume correction with constant throttle opening. In addition, ETCS performs traction control (TRC) function and some stabilization system (VSC) functions.

SCV (swirl control valve) actuator. There is SCV block between the cylinder head and the inlet manifold, which closes one of two inlets channel to each cylinder, depending on the driving conditions. The flaps are driven by vacuum actuator.

1 – SCV actuator, 2 – SCV valve, 3 – MAP sensor.

– At low speed, low load, low coolant temperature SCV is closed, air flows through one port, which increases flow speed and forms a vortex in the cylinder, for better mixture turbulization.
– At a high load, SCV opens and air flows through both ports.

Considering the air supply system features, an additional pressure sensor for the brake servo was implemented, to switch the mode that provides the specified vacuum level.

EGR system (domestic market)

Exhaust gas recirculation system of D-4 engines provides inlet of significant proportion of the exhaust gas at LeanBurn mode (much more than in traditional engines). It allows to low combustion temperature, decrease content of nitrogen oxides in the exhaust gases, reduce pumping losses at the inlet.

EGR valve is driven by DC step-motor, opening angle depends on the engine speed, coolant temperature, load and vehicle speed.

Exhaust gases from the valve flows into the EGR aluminum manifold, which uniforms stream of gases in each cylinder. Both the valve and manifold are water cooled.

NOx-converter (domestic market)

In the exhaust pipe of the Japanese models, NOx converter is installed. LeanBurn mode is accompanied by increased emission of NOx than the nitric oxide reacts with oxygen of the exhaust gas (O2), and products are accumulated on the catalyst adsorbing material in the form of nitrates (NO2).

At homogeneous mode, with a sufficiently rich mixture, the content of CO and HC in the exhaust gases increases, with its involvement in the presence of platinum dioxide (NO2) is reduced to nitrogen (N2). Simultaneously with the accumulation of nitrogen oxides converter actively captures the sulfur, which takes the useful volume of the absorbent layer, so the system can to function normally only using low-sulfur gasoline.

Ignition system – DIS-4, spark plugs with iridium center electrode (initially for overseas market – Denso SK20R11 / NGK IFR6A11, since MY2003 – Denso SK20BR11 with two additional side electrodes, for the domestic market – SK20BGR11 – protruded in the combustion chamber due to long shroud).

Type’2004 differences: L-type control system with MAF sensor, ETCS actuator with a throttle position sensor (Hall effect), absence of separate NO-converter.

Owner’S Experience

• The above mentioned typical defects of 2AZ-FE engines are relevant for -FSE engines, including the problem with the “drop head” failure (defective parts – 11400-28120, -28160, ~$5000-6000).

In addition, several specific points are added:

  1. The tendency to noticeable vibrations due to low nominal idle speed, drawdown further with minimum deviations of engine management system components operation. Sometimes the traction loss at medium speed occurs and driving performance is deteriorated. Often, the cause can not be found even by whole units replacement, although in some cases, cleaning of MAF sensor, throttle, SCV actuator, or replacement of VVT valve, ignition coil terminals, EGR forced clogging may be useful. To partially smooth discomfort from rpm subsidence helps the replacement of the engine mounts (primarily – liquid filled).
  2. Direct injection and control system has no such critical defects as first-generation (3S-FSE), and require less attention. Recommended to be extremely careful with brittle plastic parts of the injectors (~$300), sometime injectors required in case of coil deteriorating. Replacement of low-pressure electric pump and fuel tank filter often requires. Note formal recall campaigns concerning fuel pipe replacement and the fuel pump check valve for the Avensis 250.
  3. EGR operation traditionally causes a strong carbon deposit in the inlet – from the throttle to the SCV and valves, and therefore requires regular mechanical and chemical treatment. Otherwise, problems of rpm drawdown and cold start are inevitable. There is not EGR at -FSE engines for the domestic market, but it does not eliminate the need for cleaning the intake of the oil sludge.



After more than ten years since the first AZ appearance we can evaluate the series as a whole.

Specs. Power output and torque – are consistent with the average level of asian analogs, and in most cases provides enough thrust-weight ratio (except perhaps medium-SUVs).

Direct injection. D-4 did not cause significant performance gain or improvement in fuel efficiency compare to conventional motors of AZ series, and performs primarily “environmental” objectives. But increased cost of maintenance and repair of the “excess” components is enough to once again make sure of worthlessness and harm of using direct injection engines on the low-forced natural aspirated engines. Although 1..2AZ-FSE are more reliable than a terrible 3S-FSE, ordinary 1..2AZ-FE with multipoint injection are less of a problem.

Not to mention that because of an incurable idling low rpm problem (with the attendant vibrations) such cars driving is uncomfortable. Small note – in 2008 the known asian auto-repairer wrote: “but the progress is not standing still, and MFI soon be will be replaced by DI”, but in reality the D-4 history has developed somewhat differently.

Repairability. From the point of view of the manufacturer AZ considered “disposable”, as well as all the modern engines without “oversize” concept. Of course, in despair, these engines are subjected to overhaul, with cylinder block liners replacement using non-original parts or matched counterparts from other brands. The minimum cost of such work, as usual, is comparable to the price of the used engine – $1500-2000, whereas in the top-workshops complete overhaul valued at $4000-5000. As with other aspects of maintainability, here things are good – 2AZ-FE and 1AZ-FSE and shipped both to the European and the domestic markets, which has removed a lot of problems with spare parts and “second hand” engines.

Reliability. In the aggregate of most specs AZ series could be considered not bad representatives of the “3rd wave” motors, but only one critical defect of the cylinder heads ever eliminated their reputation, becoming a congenital malformation of popular models (Camry 30, RAV4 20, Highlander 20…), and undermined confidence to even later modifications.


Part 1 2003 rav4 1az-fe repair and diagnosis of camshaft, engine valve head removal

Unstable 1AZ-FSE motor rotation

Dan Hoffman

Dan is a co-founder of Engineswork. He knows everything about internal combustion engines. Ask your questions in comments down below this article - he will be glad to help you anytime.

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