Dear AndreD,

Hope you're well. I usually do not comment, when I cannot answer a specific question. That's so, in regard to your question.

I venture to raise a more basic issue. Your question implicitly raises the question as to whether the factory-original catalytic converter is likely to fail, before your soon-to-be-installed "cat back" exhaust system parts (all parts behind the catalytic converter) again need replacement. This is an important issue.

If catalytic converters' working life were known to be, say, 25 years, you'd be wise to replace the catalytic converter, right now, i.e., when new "cat-back" exhaust parts are put in. Specifically, as your car is a 1995 model, with a 25-year working life, the catalytic converter will need to be replaced by 2020-21, well within the working life of the soon-to-be-installed "cat back" parts.

However, the oldest 940s date from 1991, so are 23 years old. I recall few posts reporting catalytic converter failure.

A better source of insights into the longevity of factory-installed catalytic converters would be those who own 740s, first produced for the 1985 model year (according to Volvo VADIS, the superseded factory parts/service database).

The first 740s are 30 years old. Go to the 700 forum and ask those with older 740s/760s (those made prior to 1990): (a) if they have had to replace catalytic converters and, if so, why (internal falure [disintegration of the ceramic honeycomb], corrosion, road hazard, etc.); (b) how long ago - or at what mileage/"kilometrage" - they replaced the catalytic converter; (c) what is the model year of the car in question.

If the balance of reports show that factory-original catalytic converters installed on 740s tend to fail just after, say, 22, years, then you might consider replacing your car's catalytic converter. If the balance of reports show few catalytic converter failures, even on 30-year-old cars, then it might be better to leave alone your car's factory-installed catalytic converter.

Volvo has two separate parts for catalytic converters on '95 940s with the B230FD engine. That for cars without EGR valves is #3531256 (MSRP = $922). That for cars with EGR valves is #8603144 (MSRP = $829).

Generally, if Volvo has separate part numbers, the parts do not interchange. Therefore, I'd infer there's some difference, possibly not externally obvious, between these catalytic converters. An exception: fuel pressure regulators will interchange between Bosch and Rex/Regina cars, even though these parts have different part numbers and the Bosch unit is larger than the Rex/Regina unit.

Hope this helps.

Yours faithfully,

Spook