Your signature says you have a 1985 300D. Is that the car in question? If so, I don't think they had a trap oxidizer from the factory. The well known engine with the trap ox. is the 1987 OM603 engine. There was a recall campaign that replaced the exhaust system from the turbo back, and even replaced the turbo if it was required.

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Doug

1987 300TD x 3
2005 E320CDI