Toyota A25A (Dynamic Force 2.5)

Toyota's current 2.5-litre four, introduced with the TNGA platform — the engine of the Camry, RAV4 and Highlander since 2017, and the petrol side of their hybrids as the A25A-FXS. The 2.0 of the same family is the M20A, which shares the architecture and not the block.

Technically it is the most sophisticated engine in Toyota's volume range: both port and direct injection, a very high compression ratio, variable cooling and an unusually high thermal efficiency. The dual-injection arrangement is the diagnostically relevant part, because it means the intake-valve carbon problem that afflicts direct-injection-only engines largely does not occur here — port injectors wash the valves. A rough-running complaint on one of these should not be attributed to carbon by analogy with a European direct-injection four.

Being recent, its long-term failure patterns are not yet established, which is worth stating rather than filling with speculation. The systems that generate faults so far are the ones with the most sensors: variable cooling, the exhaust-gas recirculation circuit, and on hybrids the interaction between engine control and the hybrid strategy.