Volvo VEA petrol (B4204T)

The petrol half of Volvo's modular 2.0-litre four — the Drive-E family, which replaced the company's five- and six-cylinder engines entirely. Every petrol Volvo since has been a version of this one: T4, T5, T6 and T8 share a block, and the difference between them is boosting and electrification rather than architecture. The diesel half is the D4204T, the same block with compression ignition.

The T6 is both turbocharged and supercharged — the supercharger fills in low-speed response and disengages once the turbocharger is flowing — and the T8 adds a rear electric axle. That layering is the diagnostic reality: a performance complaint on a T6 or T8 needs the boost source identified before anything is condemned, because the symptom differs completely depending on which system is at fault.

The recurring items are the direct-injection intake-valve carbon, the high-pressure fuel pump, and — on early examples — the timing belt driving the oil pump, which is an internal wet belt with the same failure consequences as Ford's and PSA's.

B4204T alone does not identify this engine. Volvo used the same designation for the modular 2.0 turbo four of the 1990s S40 and V40, which shares nothing with it. A pre-2013 car wearing that code is the older engine.