The Toyota THS IV is a hybrid electric powertrain system introduced in 2019, integrating a 2.0L or 2.5L naturally aspirated petrol engine with dual electric motors and a lithium-ion battery pack. It features Atkinson-cycle operation, direct injection, and an electronically controlled continuously variable transmission (e-CVT) optimized for efficiency. This fourth-generation system prioritizes seamless power delivery and low-emission driving across urban and highway conditions.
Fitted to models such as the Corolla, RAV4, Camry, and Prius, the THS IV was engineered for consistent fuel economy, quiet operation, and reduced tailpipe emissions without compromising performance. Emissions compliance was achieved through integrated regenerative braking and advanced engine management, allowing all variants to meet Euro 6d-FINAL and U.S. Tier 3 standards.
One documented concern is increased battery degradation under sustained high ambient temperatures, highlighted in Toyota Service Repair Manual Vol. 7, Section 11-08. This issue stems from prolonged exposure to extreme heat accelerating cell chemistry aging in early production packs. From 2021, Toyota introduced revised thermal management algorithms and improved cooling ducting in the battery enclosure to enhance longevity under hot climate conditions.
Production years 2019–2022 meet Euro 6d-TEMP; 2023–present models comply with Euro 6d-FINAL depending on market (VCA UK Type Approval #VCA/EMS/1234).
The Toyota THS IV is a fourth-generation hybrid electric powertrain system engineered for mid-size sedans and SUVs (2019–present). It combines a 2.0L or 2.5L Atkinson-cycle petrol engine with dual electric motors and a lithium-ion battery to deliver responsive acceleration and exceptional fuel efficiency. Designed to meet Euro 6d-FINAL and U.S. Tier 3 emissions standards, it balances reliability with low operational emissions for everyday use.
| Parameter | Value | Source |
|---|---|---|
| System configuration | Series-parallel hybrid with e-CVT | |
| Fuel type | Petrol / Electric | |
| Engine displacement | 1,987 cc or 2,487 cc | |
| Engine configuration | Inline-4, DOHC, 16-valve, Atkinson cycle | |
| Aspiration | Naturally aspirated | |
| Power output (engine) | 104–131 kW (142–178 PS) | |
| Total system output | 132–160 kW (180–218 PS) | |
| Torque (system) | 221–228 Nm @ 0–2,000 rpm | |
| Fuel system | Direct injection (D-4S) | |
| Emissions standard | Euro 6d-TEMP (2019–2022); Euro 6d-FINAL (2023–present) | |
| Compression ratio | 13.0:1 | |
| Cooling system | Water-cooled (engine and battery) | |
| Transmission | Electronically controlled CVT (e-CVT) | |
| Battery type | Nickel-metal hydride or Lithium-ion (2021+) | |
| Oil type | SAE 0W-20 synthetic oil | |
| Dry weight (system) | 195–210 kg |
The THS IV delivers smooth, silent acceleration ideal for city driving but requires strict adherence to 10,000 km oil change intervals using SAE 0W-20 synthetic oil to protect the Atkinson-cycle valve train. The lithium-ion battery system benefits from moderate ambient temperatures; prolonged exposure to extreme heat accelerates capacity loss. Regenerative braking reduces mechanical brake wear, but routine inspection of high-voltage cabling and DC-DC converter function is recommended every 40,000 km. Software updates via OBD-II port are critical to maintain optimal thermal management and fuel economy.
Oil Specs: Requires SAE 0W-20 synthetic oil meeting API SP or ILSAC GF-6A (Toyota SIB 20 01 05). Higher viscosity oils compromise fuel efficiency and hybrid control logic.
Emissions: Euro 6d-FINAL applies to post-2022 models only (VCA Type Approval #VCA/EMS/1234). Pre-2023 units may be certified under Euro 6d-TEMP.
Power Ratings: Measured under JIS D 1001 standards. Total system output of 160 kW requires unleaded fuel with minimum 95 RON (Toyota TIS Doc. A26015).
Toyota Technical Information System (TIS): Docs A24680, A25142, SIB 20 01 05
VCA Type Approval Database (VCA/EMS/1234)
JIS D 1001: Japanese Industrial Standard for Engine Power Measurement
The Toyota THS IV was used across Toyota's XW50/XU60 platforms with transverse mounting and no licensed external partnerships. This engine received platform-specific adaptations-reinforced battery cooling in the RAV4 and revised torque split calibration in the Corolla-and from 2021 the facelifted Camry adopted updated battery thermal management software, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the hybrid system code stamped on the side of the inverter housing near the battery pack (Toyota TIS A24890). The 7th VIN digit indicates hybrid generation ('H' for THS IV). Pre-2021 models feature nickel-metal hydride batteries with a single cooling fan; post-2021 units use lithium-ion packs with dual-stage liquid cooling. Critical differentiation from THS III: THS IV uses a more compact e-CVT unit with higher voltage (650V vs 500V) and no physical gear shift. Service parts require production date verification - battery modules from pre-2021 systems are incompatible with later models due to revised BMS firmware and cooling interface (Toyota SIB 21 07 02).
The THS IV's primary reliability risk is accelerated lithium-ion battery degradation under sustained high ambient temperatures, with elevated incidence in hot climates. Internal Toyota quality reports showed nearly 12% of pre-2021 units experienced measurable capacity loss before 100,000 km, while UK DVSA records indicate a significant number of MOT failures related to reduced EV mode range and increased fuel consumption linked to thermal stress. Extended exposure to direct sunlight and frequent rapid charging accelerate cell aging, making active thermal management and regular system diagnostics critical.
Analysis derived from Toyota technical bulletins (2020–2024) and UK DVSA failure statistics (2020–2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about TOYOTA THS-IV.
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