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Technical Service Bulletin BMW
BMW Bulletin Number
18 01 99
Woodcliff Lake, NJ
Unnecessary Catalytic Converter Replacements
E36 with M44 engine from 1/96 prod.
Z3 with M44 engine from 10/96 prod.
E36 with M52, 852 engines from 10/95 prod.
E46 with M52 engine from 6/98 prod.
E39 with M52 engine from 3/96 prod.
Z3 with M52, 852 engines from 1/96 prod.
E38, E39, E31 with M62 engine from 1/96 prod.
E38, E31 with M73 engine from 1/95 prod.
Analysis of returned catalytic converters has proven that some converters are not defective and are replaced unnecessarily.
The reason for unnecessary converter replacements may be due to the misfire fault code(s) in conjunction with the statement "catalyst damaging" being stored in the Engine Control Module (ECM/DME).
Fault Codes 63 - 70: "Cylinder misfire detected - catalyst damaging"
If a vehicle is found with the "Check Engine" lamp on and one or more misfire faults are stored in the engine control module, the fault code description "cylinder X misfire detected - catalyst damaging" will be displayed on the diagnosis fault survey of the DIS or MoDIC.
The qualifier "catalyst damaging" is a reminder that this type of fault (cylinder misfire) may over time cause damage to the catalytic converter if it is not repaired.
Troubleshooting cylinder faults should be carried out using the DIS or MoDIC i.e. check secondary ignition system, etc.
A catalytic converter should not be replaced automatically when a - catalyst damaging" fault code is stored in the Engine Control Module.
A catalytic converter replacement is only necessary if fault codes 40, 45 or 233 (E9 hex), 234 (EA hex) are stored in the Engine Control Module which are catalytic converter efficiency or conversion faults and/or if a customer complaint of an audible rattle noise coming from the converter is verified.