Saab H-engine (B202 / B234)

Saab's four-cylinder — the H-engine — in the 900, 9000, 9-3 and 9-5, at 2.0 and 2.3 litres and in a long list of states of tune.

⚑ B202 is a SAAB designation and it looks like a BMW one. This catalogue's own alias tooling proposed it as an extension of BMW's B2 family and was refused; anybody searching a bare B2 code should establish the marque first.

It is a turbocharged engine even where the badge is quiet about it, and Saab's own engine management — APC, later Trionic — is what makes these cars behave the way they do. A boost or knock complaint on one is a question about that system, and generic turbo diagnosis misses it.

The direct ignition cassette on the later engines is the single most common failure, and its symptom is misleading: it produces a misfire or a no-start that looks like fuelling, and it fails progressively rather than suddenly. It is one part, it is well known, and it should be ruled out early.

Oil sludge in the B205/B235 is a genuine pattern on cars run on long intervals with the wrong oil — the turbocharger's feed is what blocks, and the failure reads as a turbo fault. The oil history is the first question on any of these.

Saab is gone and the parts network with it, which is usually what decides whether a repair happens.